diff --git a/src/applications/metamta/application/PhabricatorMetaMTAApplication.php b/src/applications/metamta/application/PhabricatorMetaMTAApplication.php
index 9f6633f9c4..5617c39c35 100644
--- a/src/applications/metamta/application/PhabricatorMetaMTAApplication.php
+++ b/src/applications/metamta/application/PhabricatorMetaMTAApplication.php
@@ -1,57 +1,53 @@
 <?php
 
 final class PhabricatorMetaMTAApplication extends PhabricatorApplication {
 
   public function getName() {
-    return pht('MetaMTA');
+    return pht('Mail');
   }
 
   public function getBaseURI() {
     return '/mail/';
   }
 
   public function getFontIcon() {
     return 'fa-send';
   }
 
   public function getShortDescription() {
-    return pht('Delivers Mail');
+    return pht('Send and Receive Mail');
   }
 
   public function getFlavorText() {
-    return pht('Yo dawg, we heard you like MTAs.');
+    return pht('Every program attempts to expand until it can read mail.');
   }
 
   public function getApplicationGroup() {
     return self::GROUP_ADMIN;
   }
 
   public function canUninstall() {
     return false;
   }
 
-  public function isLaunchable() {
-    return false;
-  }
-
   public function getTypeaheadURI() {
-    return null;
+    return '/mail/';
   }
 
   public function getRoutes() {
     return array(
       '/mail/' => array(
         '(query/(?P<queryKey>[^/]+)/)?' =>
           'PhabricatorMetaMTAMailListController',
         'detail/(?P<id>[1-9]\d*)/' => 'PhabricatorMetaMTAMailViewController',
         'sendgrid/' => 'PhabricatorMetaMTASendGridReceiveController',
         'mailgun/'  => 'PhabricatorMetaMTAMailgunReceiveController',
       ),
     );
   }
 
   public function getTitleGlyph() {
     return '@';
   }
 
 }
diff --git a/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php b/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php
index 938e6f656c..fd9d5a221e 100644
--- a/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php
+++ b/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php
@@ -1,111 +1,277 @@
 <?php
 
 final class PhabricatorMetaMTAMailViewController
   extends PhabricatorMetaMTAController {
 
   public function handleRequest(AphrontRequest $request) {
-    $viewer = $request->getUser();
+    $viewer = $this->getViewer();
 
     $mail = id(new PhabricatorMetaMTAMailQuery())
       ->setViewer($viewer)
       ->withIDs(array($request->getURIData('id')))
       ->executeOne();
     if (!$mail) {
       return new Aphront404Response();
     }
 
     if ($mail->hasSensitiveContent()) {
       $title = pht('Content Redacted');
     } else {
       $title = $mail->getSubject();
     }
+
     $header = id(new PHUIHeaderView())
       ->setHeader($title)
-      ->setUser($this->getRequest()->getUser())
+      ->setUser($viewer)
       ->setPolicyObject($mail);
 
+    switch ($mail->getStatus()) {
+      case PhabricatorMetaMTAMail::STATUS_QUEUE:
+        $icon = 'fa-clock-o';
+        $color = 'blue';
+        $name = pht('Queued');
+        break;
+      case PhabricatorMetaMTAMail::STATUS_SENT:
+        $icon = 'fa-envelope';
+        $color = 'green';
+        $name = pht('Sent');
+        break;
+      case PhabricatorMetaMTAMail::STATUS_FAIL:
+        $icon = 'fa-envelope';
+        $color = 'red';
+        $name = pht('Delivery Failed');
+        break;
+      case PhabricatorMetaMTAMail::STATUS_VOID:
+        $icon = 'fa-envelope';
+        $color = 'black';
+        $name = pht('Voided');
+        break;
+      default:
+        $icon = 'fa-question-circle';
+        $color = 'yellow';
+        $name = pht('Unknown');
+        break;
+    }
+
+    $header->setStatus($icon, $color, $name);
+
     $crumbs = $this->buildApplicationCrumbs()
-      ->addTextCrumb(
-        'Mail '.$mail->getID());
+      ->addTextCrumb(pht('Mail %d', $mail->getID()));
+
     $object_box = id(new PHUIObjectBoxView())
       ->setHeader($header)
-      ->addPropertyList($this->buildPropertyView($mail));
+      ->addPropertyList($this->buildMessageProperties($mail), pht('Message'))
+      ->addPropertyList($this->buildHeaderProperties($mail), pht('Headers'))
+      ->addPropertyList($this->buildDeliveryProperties($mail), pht('Delivery'))
+      ->addPropertyList($this->buildMetadataProperties($mail), pht('Metadata'));
 
     return $this->buildApplicationPage(
       array(
         $crumbs,
         $object_box,
       ),
       array(
         'title' => $title,
         'pageObjects' => array($mail->getPHID()),
       ));
   }
 
-  private function buildPropertyView(PhabricatorMetaMTAMail $mail) {
+  private function buildMessageProperties(PhabricatorMetaMTAMail $mail) {
     $viewer = $this->getViewer();
 
     $properties = id(new PHUIPropertyListView())
       ->setUser($viewer)
       ->setObject($mail);
 
-    $properties->addProperty(
-      pht('ID'),
-      $mail->getID());
-
-    $properties->addProperty(
-      pht('Status'),
-      $mail->getStatus());
-
-    if ($mail->getMessage()) {
-      $properties->addProperty(
-        pht('Status Details'),
-        $mail->getMessage());
-    }
-
-    if ($mail->getRelatedPHID()) {
-      $properties->addProperty(
-        pht('Related Object'),
-        $viewer->renderHandle($mail->getRelatedPHID()));
-    }
-
-    if ($mail->getActorPHID()) {
-      $actor_str = $viewer->renderHandle($mail->getActorPHID());
-    } else {
-      $actor_str = pht('Generated by Phabricator');
-    }
-    $properties->addProperty(
-      pht('Actor'),
-      $actor_str);
-
     if ($mail->getFrom()) {
       $from_str = $viewer->renderHandle($mail->getFrom());
     } else {
       $from_str = pht('Sent by Phabricator');
     }
     $properties->addProperty(
       pht('From'),
       $from_str);
 
     if ($mail->getToPHIDs()) {
       $to_list = $viewer->renderHandleList($mail->getToPHIDs());
     } else {
       $to_list = pht('None');
     }
     $properties->addProperty(
       pht('To'),
       $to_list);
 
     if ($mail->getCcPHIDs()) {
       $cc_list = $viewer->renderHandleList($mail->getCcPHIDs());
     } else {
       $cc_list = pht('None');
     }
     $properties->addProperty(
       pht('Cc'),
       $cc_list);
 
+    $properties->addSectionHeader(
+      pht('Message'),
+      PHUIPropertyListView::ICON_SUMMARY);
+
+    if ($mail->hasSensitiveContent()) {
+      $body = phutil_tag(
+        'em',
+        array(),
+        pht(
+          'The content of this mail is sensitive and it can not be '.
+          'viewed from the web UI.'));
+    } else {
+      $body = phutil_tag(
+        'div',
+        array(
+          'style' => 'white-space: pre-wrap',
+        ),
+        $mail->getBody());
+    }
+
+    $properties->addTextContent($body);
+
+
+    return $properties;
+  }
+
+  private function buildHeaderProperties(PhabricatorMetaMTAMail $mail) {
+    $viewer = $this->getViewer();
+
+    $properties = id(new PHUIPropertyListView())
+      ->setUser($viewer)
+      ->setStacked(true);
+
+    $headers = $mail->getDeliveredHeaders();
+    if ($headers === null) {
+      $headers = $mail->generateHeaders();
+    }
+
+    // Sort headers by name.
+    $headers = isort($headers, 0);
+
+    foreach ($headers as $header) {
+      list($key, $value) = $header;
+      $properties->addProperty($key, $value);
+    }
+
+    return $properties;
+  }
+
+  private function buildDeliveryProperties(PhabricatorMetaMTAMail $mail) {
+    $viewer = $this->getViewer();
+
+    $properties = id(new PHUIPropertyListView())
+      ->setUser($viewer);
+
+    $actors = $mail->getDeliveredActors();
+    $reasons = null;
+    if (!$actors) {
+      // TODO: We can get rid of this special-cased message after these changes
+      // have been live for a while, but provide a more tailored message for
+      // now so things are a little less confusing for users.
+      if ($mail->getStatus() == PhabricatorMetaMTAMail::STATUS_SENT) {
+        $delivery = phutil_tag(
+          'em',
+          array(),
+          pht(
+            'This is an older message that predates recording delivery '.
+            'information, so none is available.'));
+      } else {
+        $delivery = phutil_tag(
+          'em',
+          array(),
+          pht(
+            'This message has not been delivered yet, so delivery information '.
+            'is not available.'));
+      }
+    } else {
+      $actor = idx($actors, $viewer->getPHID());
+      if (!$actor) {
+        $delivery = phutil_tag(
+          'em',
+          array(),
+          pht('This message was not delivered to you.'));
+      } else {
+        $deliverable = $actor['deliverable'];
+        if ($deliverable) {
+          $delivery = pht('Delivered');
+        } else {
+          $delivery = pht('Voided');
+        }
+
+        $reasons = id(new PHUIStatusListView());
+
+        $reason_codes = $actor['reasons'];
+        if (!$reason_codes) {
+          $reason_codes = array(
+            PhabricatorMetaMTAActor::REASON_NONE,
+          );
+        }
+
+        $icon_yes = 'fa-check green';
+        $icon_no = 'fa-times red';
+
+        foreach ($reason_codes as $reason) {
+          $target = phutil_tag(
+            'strong',
+            array(),
+            PhabricatorMetaMTAActor::getReasonName($reason));
+
+          if (PhabricatorMetaMTAActor::isDeliveryReason($reason)) {
+            $icon = $icon_yes;
+          } else {
+            $icon = $icon_no;
+          }
+
+          $item = id(new PHUIStatusItemView())
+            ->setIcon($icon)
+            ->setTarget($target)
+            ->setNote(PhabricatorMetaMTAActor::getReasonDescription($reason));
+
+          $reasons->addItem($item);
+        }
+      }
+    }
+
+    $properties->addProperty(pht('Delivery'), $delivery);
+    if ($reasons) {
+      $properties->addProperty(pht('Reasons'), $reasons);
+    }
+
+    return $properties;
+  }
+
+  private function buildMetadataProperties(PhabricatorMetaMTAMail $mail) {
+    $viewer = $this->getViewer();
+
+    $properties = id(new PHUIPropertyListView())
+      ->setUser($viewer);
+
+    $details = $mail->getMessage();
+    if (!strlen($details)) {
+      $details = phutil_tag('em', array(), pht('None'));
+    }
+    $properties->addProperty(pht('Status Details'), $details);
+
+    $actor_phid = $mail->getActorPHID();
+    if ($actor_phid) {
+      $actor_str = $viewer->renderHandle($actor_phid);
+    } else {
+      $actor_str = pht('Generated by Phabricator');
+    }
+    $properties->addProperty(pht('Actor'), $actor_str);
+
+    $related_phid = $mail->getRelatedPHID();
+    if ($related_phid) {
+      $related = $viewer->renderHandle($mail->getRelatedPHID());
+    } else {
+      $related = phutil_tag('em', array(), pht('None'));
+    }
+    $properties->addProperty(pht('Related Object'), $related);
+
     return $properties;
   }
 
 }
diff --git a/src/applications/metamta/management/PhabricatorMailManagementShowOutboundWorkflow.php b/src/applications/metamta/management/PhabricatorMailManagementShowOutboundWorkflow.php
index bc8f4ccbaf..b30f2685e6 100644
--- a/src/applications/metamta/management/PhabricatorMailManagementShowOutboundWorkflow.php
+++ b/src/applications/metamta/management/PhabricatorMailManagementShowOutboundWorkflow.php
@@ -1,165 +1,180 @@
 <?php
 
 final class PhabricatorMailManagementShowOutboundWorkflow
   extends PhabricatorMailManagementWorkflow {
 
   protected function didConstruct() {
     $this
       ->setName('show-outbound')
       ->setSynopsis(pht('Show diagnostic details about outbound mail.'))
       ->setExamples(
         '**show-outbound** --id 1 --id 2')
       ->setArguments(
         array(
           array(
             'name'    => 'id',
             'param'   => 'id',
             'help'    => pht('Show details about outbound mail with given ID.'),
             'repeat'  => true,
           ),
           array(
             'name' => 'dump-html',
             'help' => pht(
               'Dump the HTML body of the mail. You can redirect it to a '.
               'file and then open it in a browser.'),
           ),
         ));
   }
 
   public function execute(PhutilArgumentParser $args) {
     $console = PhutilConsole::getConsole();
 
     $ids = $args->getArg('id');
     if (!$ids) {
       throw new PhutilArgumentUsageException(
         pht(
           "Use the '%s' flag to specify one or more messages to show.",
           '--id'));
     }
 
     $messages = id(new PhabricatorMetaMTAMail())->loadAllWhere(
       'id IN (%Ld)',
       $ids);
 
     if ($ids) {
       $ids = array_fuse($ids);
       $missing = array_diff_key($ids, $messages);
       if ($missing) {
         throw new PhutilArgumentUsageException(
           pht(
             'Some specified messages do not exist: %s',
             implode(', ', array_keys($missing))));
       }
     }
 
     $last_key = last_key($messages);
     foreach ($messages as $message_key => $message) {
       if ($args->getArg('dump-html')) {
         $html_body = $message->getHTMLBody();
         if (strlen($html_body)) {
           $template =
             "<!doctype html><html><body>{$html_body}</body></html>";
           $console->writeOut("%s\n", $html_body);
         } else {
           $console->writeErr(
             "%s\n",
             pht('(This message has no HTML body.)'));
         }
         continue;
       }
 
       $info = array();
 
       $info[] = pht('PROPERTIES');
       $info[] = pht('ID: %d', $message->getID());
       $info[] = pht('Status: %s', $message->getStatus());
       $info[] = pht('Related PHID: %s', $message->getRelatedPHID());
       $info[] = pht('Message: %s', $message->getMessage());
 
+      $ignore = array(
+        'body' => true,
+        'html-body' => true,
+        'headers' => true,
+        'attachments' => true,
+        'headers.sent' => true,
+        'authors.sent' => true,
+      );
+
       $info[] = null;
       $info[] = pht('PARAMETERS');
       $parameters = $message->getParameters();
       foreach ($parameters as $key => $value) {
-        if ($key == 'body') {
-          continue;
-        }
-
-        if ($key == 'html-body') {
-          continue;
-        }
-
-        if ($key == 'headers') {
-          continue;
-        }
-
-        if ($key == 'attachments') {
+        if (isset($ignore[$key])) {
           continue;
         }
 
         if (!is_scalar($value)) {
           $value = json_encode($value);
         }
 
         $info[] = pht('%s: %s', $key, $value);
       }
 
       $info[] = null;
       $info[] = pht('HEADERS');
-      foreach (idx($parameters, 'headers', array()) as $header) {
+
+      $headers = $message->getDeliveredHeaders();
+      if (!$headers) {
+        $headers = $message->generateHeaders();
+      }
+
+      foreach ($headers as $header) {
         list($name, $value) = $header;
         $info[] = "{$name}: {$value}";
       }
 
       $attachments = idx($parameters, 'attachments');
       if ($attachments) {
         $info[] = null;
         $info[] = pht('ATTACHMENTS');
         foreach ($attachments as $attachment) {
           $info[] = idx($attachment, 'filename', pht('Unnamed File'));
         }
       }
 
-      $actors = $message->loadAllActors();
-      $actors = array_select_keys(
-        $actors,
-        array_merge($message->getToPHIDs(), $message->getCcPHIDs()));
-      $info[] = null;
-      $info[] = pht('RECIPIENTS');
-      foreach ($actors as $actor) {
-        if ($actor->isDeliverable()) {
-          $info[] = '  '.coalesce($actor->getName(), $actor->getPHID());
-        } else {
-          $info[] = '! '.coalesce($actor->getName(), $actor->getPHID());
-        }
-        foreach ($actor->getDeliverabilityReasons() as $reason) {
-          $desc = PhabricatorMetaMTAActor::getReasonDescription($reason);
-          $info[] = '    - '.$desc;
+      $all_actors = $message->loadAllActors();
+
+      $actors = $message->getDeliveredActors();
+      if ($actors) {
+        $info[] = null;
+        $info[] = pht('RECIPIENTS');
+        foreach ($actors as $actor_phid => $actor_info) {
+          $actor = idx($all_actors, $actor_phid);
+          if ($actor) {
+            $actor_name = coalesce($actor->getName(), $actor_phid);
+          } else {
+            $actor_name = $actor_phid;
+          }
+
+          $deliverable = $actor_info['deliverable'];
+          if ($deliverable) {
+            $info[] = '  '.$actor_name;
+          } else {
+            $info[] = '! '.$actor_name;
+          }
+
+          $reasons = $actor_info['reasons'];
+          foreach ($reasons as $reason) {
+            $name = PhabricatorMetaMTAActor::getReasonName($reason);
+            $desc = PhabricatorMetaMTAActor::getReasonDescription($reason);
+            $info[] = '    - '.$name.': '.$desc;
+          }
         }
       }
 
       $info[] = null;
       $info[] = pht('TEXT BODY');
       if (strlen($message->getBody())) {
         $info[] = $message->getBody();
       } else {
         $info[] = pht('(This message has no text body.)');
       }
 
       $info[] = null;
       $info[] = pht('HTML BODY');
       if (strlen($message->getHTMLBody())) {
         $info[] = $message->getHTMLBody();
         $info[] = null;
       } else {
         $info[] = pht('(This message has no HTML body.)');
       }
 
       $console->writeOut('%s', implode("\n", $info));
 
       if ($message_key != $last_key) {
         $console->writeOut("\n%s\n\n", str_repeat('-', 80));
       }
     }
   }
 
 }
diff --git a/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php b/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php
index c907bf1050..dcc548e0f5 100644
--- a/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php
+++ b/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php
@@ -1,79 +1,108 @@
 <?php
 
 final class PhabricatorMailManagementVolumeWorkflow
   extends PhabricatorMailManagementWorkflow {
 
   protected function didConstruct() {
     $this
       ->setName('volume')
       ->setSynopsis(
         pht('Show how much mail users have received in the last 30 days.'))
       ->setExamples(
         '**volume**')
       ->setArguments(
         array(
         ));
   }
 
   public function execute(PhutilArgumentParser $args) {
     $console = PhutilConsole::getConsole();
     $viewer = $this->getViewer();
 
     $since = (PhabricatorTime::getNow() - phutil_units('30 days in seconds'));
     $until = PhabricatorTime::getNow();
 
     $mails = id(new PhabricatorMetaMTAMailQuery())
       ->setViewer($viewer)
       ->withDateCreatedBetween($since, $until)
       ->execute();
 
     $unfiltered = array();
+    $delivered = array();
 
     foreach ($mails as $mail) {
+      // Count messages we attempted to deliver. This includes messages which
+      // were voided by preferences or other rules.
       $unfiltered_actors = mpull($mail->loadAllActors(), 'getPHID');
       foreach ($unfiltered_actors as $phid) {
         if (empty($unfiltered[$phid])) {
           $unfiltered[$phid] = 0;
         }
         $unfiltered[$phid]++;
       }
+
+      // Now, count mail we actually delivered.
+      $result = $mail->getDeliveredActors();
+      if ($result) {
+        foreach ($result as $actor_phid => $actor_info) {
+          if (!$actor_info['deliverable']) {
+            continue;
+          }
+          if (empty($delivered[$actor_phid])) {
+            $delivered[$actor_phid] = 0;
+          }
+          $delivered[$actor_phid]++;
+        }
+      }
     }
 
+    // Sort users by delivered mail, then unfiltered mail.
+    arsort($delivered);
     arsort($unfiltered);
+    $delivered = $delivered + array_fill_keys(array_keys($unfiltered), 0);
 
     $table = id(new PhutilConsoleTable())
       ->setBorders(true)
       ->addColumn(
         'user',
         array(
           'title' => pht('User'),
         ))
       ->addColumn(
         'unfiltered',
         array(
           'title' => pht('Unfiltered'),
+        ))
+      ->addColumn(
+        'delivered',
+        array(
+          'title' => pht('Delivered'),
         ));
 
     $handles = $viewer->loadHandles(array_keys($unfiltered));
     $names = mpull(iterator_to_array($handles), 'getName', 'getPHID');
 
-    foreach ($unfiltered as $phid => $count) {
+    foreach ($delivered as $phid => $delivered_count) {
+      $unfiltered_count = idx($unfiltered, $phid, 0);
       $table->addRow(
         array(
           'user' => idx($names, $phid),
-          'unfiltered' => $count,
+          'unfiltered' => $unfiltered_count,
+          'delivered' => $delivered_count,
         ));
     }
 
     $table->draw();
 
     echo "\n";
     echo pht('Mail sent in the last 30 days.')."\n";
     echo pht(
-      '"Unfiltered" is raw volume before preferences were applied.')."\n";
+      '"Unfiltered" is raw volume before rules applied.')."\n";
+    echo pht(
+      '"Delivered" shows email actually sent.')."\n";
     echo "\n";
 
     return 0;
   }
 
 }
diff --git a/src/applications/metamta/query/PhabricatorMetaMTAActor.php b/src/applications/metamta/query/PhabricatorMetaMTAActor.php
index 281e7fb90c..59e3f297de 100644
--- a/src/applications/metamta/query/PhabricatorMetaMTAActor.php
+++ b/src/applications/metamta/query/PhabricatorMetaMTAActor.php
@@ -1,121 +1,156 @@
 <?php
 
 final class PhabricatorMetaMTAActor extends Phobject {
 
   const STATUS_DELIVERABLE = 'deliverable';
   const STATUS_UNDELIVERABLE = 'undeliverable';
 
+  const REASON_NONE = 'none';
   const REASON_UNLOADABLE = 'unloadable';
   const REASON_UNMAILABLE = 'unmailable';
   const REASON_NO_ADDRESS = 'noaddress';
   const REASON_DISABLED = 'disabled';
   const REASON_MAIL_DISABLED = 'maildisabled';
   const REASON_EXTERNAL_TYPE = 'exernaltype';
   const REASON_RESPONSE = 'response';
   const REASON_SELF = 'self';
   const REASON_MAILTAGS = 'mailtags';
   const REASON_BOT = 'bot';
   const REASON_FORCE = 'force';
   const REASON_FORCE_HERALD = 'force-herald';
 
   private $phid;
   private $emailAddress;
   private $name;
   private $status = self::STATUS_DELIVERABLE;
   private $reasons = array();
 
   public function setName($name) {
     $this->name = $name;
     return $this;
   }
 
   public function getName() {
     return $this->name;
   }
 
   public function setEmailAddress($email_address) {
     $this->emailAddress = $email_address;
     return $this;
   }
 
   public function getEmailAddress() {
     return $this->emailAddress;
   }
 
   public function setPHID($phid) {
     $this->phid = $phid;
     return $this;
   }
 
   public function getPHID() {
     return $this->phid;
   }
 
   public function setUndeliverable($reason) {
     $this->reasons[] = $reason;
     $this->status = self::STATUS_UNDELIVERABLE;
     return $this;
   }
 
   public function setDeliverable($reason) {
     $this->reasons[] = $reason;
     $this->status = self::STATUS_DELIVERABLE;
     return $this;
   }
 
   public function isDeliverable() {
     return ($this->status === self::STATUS_DELIVERABLE);
   }
 
   public function getDeliverabilityReasons() {
     return $this->reasons;
   }
 
+  public static function isDeliveryReason($reason) {
+    switch ($reason) {
+      case self::REASON_NONE:
+      case self::REASON_FORCE:
+      case self::REASON_FORCE_HERALD:
+        return true;
+      default:
+        // All other reasons cause the message to not be delivered.
+        return false;
+    }
+  }
+
+  public static function getReasonName($reason) {
+    $names = array(
+      self::REASON_NONE => pht('None'),
+      self::REASON_DISABLED => pht('Disabled Recipient'),
+      self::REASON_BOT => pht('Bot Recipient'),
+      self::REASON_NO_ADDRESS => pht('No Address'),
+      self::REASON_EXTERNAL_TYPE => pht('External Recipient'),
+      self::REASON_UNMAILABLE => pht('Not Mailable'),
+      self::REASON_RESPONSE => pht('Similar Reply'),
+      self::REASON_SELF => pht('Self Mail'),
+      self::REASON_MAIL_DISABLED => pht('Mail Disabled'),
+      self::REASON_MAILTAGS => pht('Mail Tags'),
+      self::REASON_UNLOADABLE => pht('Bad Recipient'),
+      self::REASON_FORCE => pht('Forced Mail'),
+      self::REASON_FORCE_HERALD => pht('Forced by Herald'),
+    );
+
+    return idx($names, $reason, pht('Unknown ("%s")', $reason));
+  }
+
   public static function getReasonDescription($reason) {
     $descriptions = array(
+      self::REASON_NONE => pht(
+        'No special rules affected this mail.'),
       self::REASON_DISABLED => pht(
         'This user is disabled; disabled users do not receive mail.'),
       self::REASON_BOT => pht(
         'This user is a bot; bot accounts do not receive mail.'),
       self::REASON_NO_ADDRESS => pht(
         'Unable to load an email address for this PHID.'),
       self::REASON_EXTERNAL_TYPE => pht(
         'Only external accounts of type "email" are deliverable; this '.
         'account has a different type.'),
       self::REASON_UNMAILABLE => pht(
         'This PHID type does not correspond to a mailable object.'),
       self::REASON_RESPONSE => pht(
         'This message is a response to another email message, and this '.
         'recipient received the original email message, so we are not '.
         'sending them this substantially similar message (for example, '.
         'the sender used "Reply All" instead of "Reply" in response to '.
         'mail from Phabricator).'),
       self::REASON_SELF => pht(
         'This recipient is the user whose actions caused delivery of '.
         'this message, but they have set preferences so they do not '.
         'receive mail about their own actions (Settings > Email '.
         'Preferences > Self Actions).'),
       self::REASON_MAIL_DISABLED => pht(
         'This recipient has disabled all email notifications '.
         '(Settings > Email Preferences > Email Notifications).'),
       self::REASON_MAILTAGS => pht(
         'This mail has tags which control which users receive it, and '.
         'this recipient has not elected to receive mail with any of '.
         'the tags on this message (Settings > Email Preferences).'),
       self::REASON_UNLOADABLE => pht(
         'Unable to load user record for this PHID.'),
       self::REASON_FORCE => pht(
         'Delivery of this mail is forced and ignores deliver preferences. '.
         'Mail which uses forced delivery is usually related to account '.
         'management or authentication. For example, password reset email '.
         'ignores mail preferences.'),
       self::REASON_FORCE_HERALD => pht(
         'This recipient was added by a "Send me an Email" rule in Herald, '.
         'which overrides some delivery settings.'),
     );
 
     return idx($descriptions, $reason, pht('Unknown Reason ("%s")', $reason));
   }
 
 
 }
diff --git a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
index ee09fa730f..38aae37e02 100644
--- a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
+++ b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
@@ -1,1080 +1,1109 @@
 <?php
 
 /**
  * @task recipients   Managing Recipients
  */
 final class PhabricatorMetaMTAMail
   extends PhabricatorMetaMTADAO
   implements PhabricatorPolicyInterface {
 
   const STATUS_QUEUE = 'queued';
   const STATUS_SENT  = 'sent';
   const STATUS_FAIL  = 'fail';
   const STATUS_VOID  = 'void';
 
   const RETRY_DELAY   = 5;
 
   protected $actorPHID;
   protected $parameters;
   protected $status;
   protected $message;
   protected $relatedPHID;
 
   private $recipientExpansionMap;
 
   public function __construct() {
 
     $this->status     = self::STATUS_QUEUE;
     $this->parameters = array('sensitive' => true);
 
     parent::__construct();
   }
 
   protected function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,
       self::CONFIG_SERIALIZATION => array(
         'parameters'  => self::SERIALIZATION_JSON,
       ),
       self::CONFIG_COLUMN_SCHEMA => array(
         'actorPHID' => 'phid?',
         'status' => 'text32',
         'relatedPHID' => 'phid?',
 
         // T6203/NULLABILITY
         // This should just be empty if there's no body.
         'message' => 'text?',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'status' => array(
           'columns' => array('status'),
         ),
         'key_actorPHID' => array(
           'columns' => array('actorPHID'),
         ),
         'relatedPHID' => array(
           'columns' => array('relatedPHID'),
         ),
         'key_created' => array(
           'columns' => array('dateCreated'),
         ),
       ),
     ) + parent::getConfiguration();
   }
 
   public function generatePHID() {
     return PhabricatorPHID::generateNewPHID(
       PhabricatorMetaMTAMailPHIDType::TYPECONST);
   }
 
   protected function setParam($param, $value) {
     $this->parameters[$param] = $value;
     return $this;
   }
 
   protected function getParam($param, $default = null) {
     return idx($this->parameters, $param, $default);
   }
 
   /**
    * These tags are used to allow users to opt out of receiving certain types
    * of mail, like updates when a task's projects change.
    *
    * @param list<const>
    * @return this
    */
   public function setMailTags(array $tags) {
     $this->setParam('mailtags', array_unique($tags));
     return $this;
   }
 
   public function getMailTags() {
     return $this->getParam('mailtags', array());
   }
 
   /**
    * In Gmail, conversations will be broken if you reply to a thread and the
    * server sends back a response without referencing your Message-ID, even if
    * it references a Message-ID earlier in the thread. To avoid this, use the
    * parent email's message ID explicitly if it's available. This overwrites the
    * "In-Reply-To" and "References" headers we would otherwise generate. This
    * needs to be set whenever an action is triggered by an email message. See
    * T251 for more details.
    *
    * @param   string The "Message-ID" of the email which precedes this one.
    * @return  this
    */
   public function setParentMessageID($id) {
     $this->setParam('parent-message-id', $id);
     return $this;
   }
 
   public function getParentMessageID() {
     return $this->getParam('parent-message-id');
   }
 
   public function getSubject() {
     return $this->getParam('subject');
   }
 
   public function addTos(array $phids) {
     $phids = array_unique($phids);
     $this->setParam('to', $phids);
     return $this;
   }
 
   public function addRawTos(array $raw_email) {
 
     // Strip addresses down to bare emails, since the MailAdapter API currently
     // requires we pass it just the address (like `alincoln@logcabin.org`), not
     // a full string like `"Abraham Lincoln" <alincoln@logcabin.org>`.
     foreach ($raw_email as $key => $email) {
       $object = new PhutilEmailAddress($email);
       $raw_email[$key] = $object->getAddress();
     }
 
     $this->setParam('raw-to', $raw_email);
     return $this;
   }
 
   public function addCCs(array $phids) {
     $phids = array_unique($phids);
     $this->setParam('cc', $phids);
     return $this;
   }
 
   public function setExcludeMailRecipientPHIDs(array $exclude) {
     $this->setParam('exclude', $exclude);
     return $this;
   }
 
   private function getExcludeMailRecipientPHIDs() {
     return $this->getParam('exclude', array());
   }
 
   public function setForceHeraldMailRecipientPHIDs(array $force) {
     $this->setParam('herald-force-recipients', $force);
     return $this;
   }
 
   private function getForceHeraldMailRecipientPHIDs() {
     return $this->getParam('herald-force-recipients', array());
   }
 
   public function getTranslation(array $objects) {
     $default_translation = PhabricatorEnv::getEnvConfig('translation.provider');
     $return = null;
     $recipients = array_merge(
       idx($this->parameters, 'to', array()),
       idx($this->parameters, 'cc', array()));
     foreach (array_select_keys($objects, $recipients) as $object) {
       $translation = null;
       if ($object instanceof PhabricatorUser) {
         $translation = $object->getTranslation();
       }
       if (!$translation) {
         $translation = $default_translation;
       }
       if ($return && $translation != $return) {
         return $default_translation;
       }
       $return = $translation;
     }
 
     if (!$return) {
       $return = $default_translation;
     }
 
     return $return;
   }
 
   public function addPHIDHeaders($name, array $phids) {
     $phids = array_unique($phids);
     foreach ($phids as $phid) {
       $this->addHeader($name, '<'.$phid.'>');
     }
     return $this;
   }
 
   public function addHeader($name, $value) {
     $this->parameters['headers'][] = array($name, $value);
     return $this;
   }
 
   public function addAttachment(PhabricatorMetaMTAAttachment $attachment) {
     $this->parameters['attachments'][] = $attachment->toDictionary();
     return $this;
   }
 
   public function getAttachments() {
     $dicts = $this->getParam('attachments');
 
     $result = array();
     foreach ($dicts as $dict) {
       $result[] = PhabricatorMetaMTAAttachment::newFromDictionary($dict);
     }
     return $result;
   }
 
   public function setAttachments(array $attachments) {
     assert_instances_of($attachments, 'PhabricatorMetaMTAAttachment');
     $this->setParam('attachments', mpull($attachments, 'toDictionary'));
     return $this;
   }
 
   public function setFrom($from) {
     $this->setParam('from', $from);
     $this->setActorPHID($from);
     return $this;
   }
 
   public function getFrom() {
     return $this->getParam('from');
   }
 
   public function setRawFrom($raw_email, $raw_name) {
     $this->setParam('raw-from', array($raw_email, $raw_name));
     return $this;
   }
 
   public function setReplyTo($reply_to) {
     $this->setParam('reply-to', $reply_to);
     return $this;
   }
 
   public function setSubject($subject) {
     $this->setParam('subject', $subject);
     return $this;
   }
 
   public function setSubjectPrefix($prefix) {
     $this->setParam('subject-prefix', $prefix);
     return $this;
   }
 
   public function setVarySubjectPrefix($prefix) {
     $this->setParam('vary-subject-prefix', $prefix);
     return $this;
   }
 
   public function setBody($body) {
     $this->setParam('body', $body);
     return $this;
   }
 
   public function setSensitiveContent($bool) {
     $this->setParam('sensitive', $bool);
     return $this;
   }
 
   public function hasSensitiveContent() {
     return $this->getParam('sensitive', true);
   }
 
   public function setHTMLBody($html) {
     $this->setParam('html-body', $html);
     return $this;
   }
 
   public function getBody() {
     return $this->getParam('body');
   }
 
   public function getHTMLBody() {
     return $this->getParam('html-body');
   }
 
   public function setIsErrorEmail($is_error) {
     $this->setParam('is-error', $is_error);
     return $this;
   }
 
   public function getIsErrorEmail() {
     return $this->getParam('is-error', false);
   }
 
   public function getToPHIDs() {
     return $this->getParam('to', array());
   }
 
   public function getRawToAddresses() {
     return $this->getParam('raw-to', array());
   }
 
   public function getCcPHIDs() {
     return $this->getParam('cc', array());
   }
 
   /**
    * Force delivery of a message, even if recipients have preferences which
    * would otherwise drop the message.
    *
    * This is primarily intended to let users who don't want any email still
    * receive things like password resets.
    *
    * @param bool  True to force delivery despite user preferences.
    * @return this
    */
   public function setForceDelivery($force) {
     $this->setParam('force', $force);
     return $this;
   }
 
   public function getForceDelivery() {
     return $this->getParam('force', false);
   }
 
   /**
    * Flag that this is an auto-generated bulk message and should have bulk
    * headers added to it if appropriate. Broadly, this means some flavor of
    * "Precedence: bulk" or similar, but is implementation and configuration
    * dependent.
    *
    * @param bool  True if the mail is automated bulk mail.
    * @return this
    */
   public function setIsBulk($is_bulk) {
     $this->setParam('is-bulk', $is_bulk);
     return $this;
   }
 
   /**
    * Use this method to set an ID used for message threading. MetaMTA will
    * set appropriate headers (Message-ID, In-Reply-To, References and
    * Thread-Index) based on the capabilities of the underlying mailer.
    *
    * @param string  Unique identifier, appropriate for use in a Message-ID,
    *                In-Reply-To or References headers.
    * @param bool    If true, indicates this is the first message in the thread.
    * @return this
    */
   public function setThreadID($thread_id, $is_first_message = false) {
     $this->setParam('thread-id', $thread_id);
     $this->setParam('is-first-message', $is_first_message);
     return $this;
   }
 
   /**
    * Save a newly created mail to the database. The mail will eventually be
    * delivered by the MetaMTA daemon.
    *
    * @return this
    */
   public function saveAndSend() {
     return $this->save();
   }
 
   public function save() {
     if ($this->getID()) {
       return parent::save();
     }
 
     // NOTE: When mail is sent from CLI scripts that run tasks in-process, we
     // may re-enter this method from within scheduleTask(). The implementation
     // is intended to avoid anything awkward if we end up reentering this
     // method.
 
     $this->openTransaction();
       // Save to generate a mail ID and PHID.
       $result = parent::save();
 
       // Write the recipient edges.
       $editor = new PhabricatorEdgeEditor();
       $edge_type = PhabricatorMetaMTAMailHasRecipientEdgeType::EDGECONST;
       $recipient_phids = array_merge(
         $this->getToPHIDs(),
         $this->getCcPHIDs());
       $expanded_phids = $this->expandRecipients($recipient_phids);
       $all_phids = array_unique(array_merge(
         $recipient_phids,
         $expanded_phids));
       foreach ($all_phids as $curr_phid) {
         $editor->addEdge($this->getPHID(), $edge_type, $curr_phid);
       }
       $editor->save();
 
       // Queue a task to send this mail.
       $mailer_task = PhabricatorWorker::scheduleTask(
         'PhabricatorMetaMTAWorker',
         $this->getID(),
         array(
           'priority' => PhabricatorWorker::PRIORITY_ALERTS,
         ));
 
     $this->saveTransaction();
 
     return $result;
   }
 
   public function buildDefaultMailer() {
     return PhabricatorEnv::newObjectFromConfig('metamta.mail-adapter');
   }
 
 
   /**
    * Attempt to deliver an email immediately, in this process.
    *
    * @param bool  Try to deliver this email even if it has already been
    *              delivered or is in backoff after a failed delivery attempt.
    * @param PhabricatorMailImplementationAdapter Use a specific mail adapter,
    *              instead of the default.
    *
    * @return void
    */
   public function sendNow(
     $force_send = false,
     PhabricatorMailImplementationAdapter $mailer = null) {
 
     if ($mailer === null) {
       $mailer = $this->buildDefaultMailer();
     }
 
     if (!$force_send) {
       if ($this->getStatus() != self::STATUS_QUEUE) {
         throw new Exception(pht('Trying to send an already-sent mail!'));
       }
     }
 
     try {
+      $headers = $this->generateHeaders();
+
       $params = $this->parameters;
 
       $actors = $this->loadAllActors();
       $deliverable_actors = $this->filterDeliverableActors($actors);
 
       $default_from = PhabricatorEnv::getEnvConfig('metamta.default-address');
       if (empty($params['from'])) {
         $mailer->setFrom($default_from);
       }
 
       $is_first = idx($params, 'is-first-message');
       unset($params['is-first-message']);
 
       $is_threaded = (bool)idx($params, 'thread-id');
 
       $reply_to_name = idx($params, 'reply-to-name', '');
       unset($params['reply-to-name']);
 
       $add_cc = array();
       $add_to = array();
 
       // Only try to use preferences if everything is multiplexed, so we
       // get consistent behavior.
       $use_prefs = self::shouldMultiplexAllMail();
 
       $prefs = null;
       if ($use_prefs) {
 
         // If multiplexing is enabled, some recipients will be in "Cc"
         // rather than "To". We'll move them to "To" later (or supply a
         // dummy "To") but need to look for the recipient in either the
         // "To" or "Cc" fields here.
         $target_phid = head(idx($params, 'to', array()));
         if (!$target_phid) {
           $target_phid = head(idx($params, 'cc', array()));
         }
 
         if ($target_phid) {
           $user = id(new PhabricatorUser())->loadOneWhere(
             'phid = %s',
             $target_phid);
           if ($user) {
             $prefs = $user->loadPreferences();
           }
         }
       }
 
       foreach ($params as $key => $value) {
         switch ($key) {
           case 'raw-from':
             list($from_email, $from_name) = $value;
             $mailer->setFrom($from_email, $from_name);
             break;
           case 'from':
             $from = $value;
             $actor_email = null;
             $actor_name = null;
             $actor = idx($actors, $from);
             if ($actor) {
               $actor_email = $actor->getEmailAddress();
               $actor_name = $actor->getName();
             }
             $can_send_as_user = $actor_email &&
               PhabricatorEnv::getEnvConfig('metamta.can-send-as-user');
 
             if ($can_send_as_user) {
               $mailer->setFrom($actor_email, $actor_name);
             } else {
               $from_email = coalesce($actor_email, $default_from);
               $from_name = coalesce($actor_name, pht('Phabricator'));
 
               if (empty($params['reply-to'])) {
                 $params['reply-to'] = $from_email;
                 $params['reply-to-name'] = $from_name;
               }
 
               $mailer->setFrom($default_from, $from_name);
             }
             break;
           case 'reply-to':
             $mailer->addReplyTo($value, $reply_to_name);
             break;
           case 'to':
             $to_phids = $this->expandRecipients($value);
             $to_actors = array_select_keys($deliverable_actors, $to_phids);
             $add_to = array_merge(
               $add_to,
               mpull($to_actors, 'getEmailAddress'));
             break;
           case 'raw-to':
             $add_to = array_merge($add_to, $value);
             break;
           case 'cc':
             $cc_phids = $this->expandRecipients($value);
             $cc_actors = array_select_keys($deliverable_actors, $cc_phids);
             $add_cc = array_merge(
               $add_cc,
               mpull($cc_actors, 'getEmailAddress'));
             break;
-          case 'headers':
-            foreach ($value as $pair) {
-              list($header_key, $header_value) = $pair;
-
-              // NOTE: If we have \n in a header, SES rejects the email.
-              $header_value = str_replace("\n", ' ', $header_value);
-
-              $mailer->addHeader($header_key, $header_value);
-            }
-            break;
           case 'attachments':
             $value = $this->getAttachments();
             foreach ($value as $attachment) {
               $mailer->addAttachment(
                 $attachment->getData(),
                 $attachment->getFilename(),
                 $attachment->getMimeType());
             }
             break;
           case 'subject':
             $subject = array();
 
             if ($is_threaded) {
               $add_re = PhabricatorEnv::getEnvConfig('metamta.re-prefix');
 
               if ($prefs) {
                 $add_re = $prefs->getPreference(
                   PhabricatorUserPreferences::PREFERENCE_RE_PREFIX,
                   $add_re);
               }
 
               if ($add_re) {
                 $subject[] = 'Re:';
               }
             }
 
             $subject[] = trim(idx($params, 'subject-prefix'));
 
             $vary_prefix = idx($params, 'vary-subject-prefix');
             if ($vary_prefix != '') {
               $use_subject = PhabricatorEnv::getEnvConfig(
                 'metamta.vary-subjects');
 
               if ($prefs) {
                 $use_subject = $prefs->getPreference(
                   PhabricatorUserPreferences::PREFERENCE_VARY_SUBJECT,
                   $use_subject);
               }
 
               if ($use_subject) {
                 $subject[] = $vary_prefix;
               }
             }
 
             $subject[] = $value;
 
             $mailer->setSubject(implode(' ', array_filter($subject)));
             break;
-          case 'is-bulk':
-            if ($value) {
-              $mailer->addHeader('Precedence', 'bulk');
-            }
-            break;
           case 'thread-id':
 
             // NOTE: Gmail freaks out about In-Reply-To and References which
             // aren't in the form "<string@domain.tld>"; this is also required
             // by RFC 2822, although some clients are more liberal in what they
             // accept.
             $domain = PhabricatorEnv::getEnvConfig('metamta.domain');
             $value = '<'.$value.'@'.$domain.'>';
 
             if ($is_first && $mailer->supportsMessageIDHeader()) {
-              $mailer->addHeader('Message-ID',  $value);
+              $headers[] = array('Message-ID',  $value);
             } else {
               $in_reply_to = $value;
               $references = array($value);
               $parent_id = $this->getParentMessageID();
               if ($parent_id) {
                 $in_reply_to = $parent_id;
                 // By RFC 2822, the most immediate parent should appear last
                 // in the "References" header, so this order is intentional.
                 $references[] = $parent_id;
               }
               $references = implode(' ', $references);
-              $mailer->addHeader('In-Reply-To', $in_reply_to);
-              $mailer->addHeader('References',  $references);
+              $headers[] = array('In-Reply-To', $in_reply_to);
+              $headers[] = array('References',  $references);
             }
             $thread_index = $this->generateThreadIndex($value, $is_first);
-            $mailer->addHeader('Thread-Index', $thread_index);
-            break;
-          case 'mailtags':
-            // Handled below.
-            break;
-          case 'subject-prefix':
-          case 'vary-subject-prefix':
-            // Handled above.
+            $headers[] = array('Thread-Index', $thread_index);
             break;
           default:
-            // Just discard.
+            // Other parameters are handled elsewhere or are not relevant to
+            // constructing the message.
+            break;
         }
       }
 
       $body = idx($params, 'body', '');
       $max = PhabricatorEnv::getEnvConfig('metamta.email-body-limit');
       if (strlen($body) > $max) {
         $body = id(new PhutilUTF8StringTruncator())
           ->setMaximumBytes($max)
           ->truncateString($body);
         $body .= "\n";
         $body .= pht('(This email was truncated at %d bytes.)', $max);
       }
       $mailer->setBody($body);
 
       $html_emails = false;
       if ($use_prefs && $prefs) {
         $html_emails = $prefs->getPreference(
           PhabricatorUserPreferences::PREFERENCE_HTML_EMAILS,
           $html_emails);
       }
 
       if ($html_emails && isset($params['html-body'])) {
         $mailer->setHTMLBody($params['html-body']);
       }
 
+      // Pass the headers to the mailer, then save the state so we can show
+      // them in the web UI.
+      foreach ($headers as $header) {
+        list($header_key, $header_value) = $header;
+        $mailer->addHeader($header_key, $header_value);
+      }
+      $this->setParam('headers.sent', $headers);
+
+      // Save the final deliverability outcomes and reasoning so we can
+      // explain why things happened the way they did.
+      $actor_list = array();
+      foreach ($actors as $actor) {
+        $actor_list[$actor->getPHID()] = array(
+          'deliverable' => $actor->isDeliverable(),
+          'reasons' => $actor->getDeliverabilityReasons(),
+        );
+      }
+      $this->setParam('actors.sent', $actor_list);
+
       if (!$add_to && !$add_cc) {
         $this->setStatus(self::STATUS_VOID);
         $this->setMessage(
           pht(
             'Message has no valid recipients: all To/Cc are disabled, '.
             'invalid, or configured not to receive this mail.'));
         return $this->save();
       }
 
       if ($this->getIsErrorEmail()) {
         $all_recipients = array_merge($add_to, $add_cc);
         if ($this->shouldRateLimitMail($all_recipients)) {
           $this->setStatus(self::STATUS_VOID);
           $this->setMessage(
             pht(
               'This is an error email, but one or more recipients have '.
               'exceeded the error email rate limit. Declining to deliver '.
               'message.'));
           return $this->save();
         }
       }
 
       if (PhabricatorEnv::getEnvConfig('phabricator.silent')) {
         $this->setStatus(self::STATUS_VOID);
         $this->setMessage(
           pht(
             'Phabricator is running in silent mode. See `%s` '.
             'in the configuration to change this setting.',
             'phabricator.silent'));
         return $this->save();
       }
 
-      $mailer->addHeader('X-Phabricator-Sent-This-Message', 'Yes');
-      $mailer->addHeader('X-Mail-Transport-Agent', 'MetaMTA');
-
-      // Some clients respect this to suppress OOF and other auto-responses.
-      $mailer->addHeader('X-Auto-Response-Suppress', 'All');
-
-      // If the message has mailtags, filter out any recipients who don't want
-      // to receive this type of mail.
-      $mailtags = $this->getParam('mailtags');
-      if ($mailtags) {
-        $tag_header = array();
-        foreach ($mailtags as $mailtag) {
-          $tag_header[] = '<'.$mailtag.'>';
-        }
-        $tag_header = implode(', ', $tag_header);
-        $mailer->addHeader('X-Phabricator-Mail-Tags', $tag_header);
-      }
-
       // Some mailers require a valid "To:" in order to deliver mail. If we
       // don't have any "To:", try to fill it in with a placeholder "To:".
       // If that also fails, move the "Cc:" line to "To:".
       if (!$add_to) {
         $placeholder_key = 'metamta.placeholder-to-recipient';
         $placeholder = PhabricatorEnv::getEnvConfig($placeholder_key);
         if ($placeholder !== null) {
           $add_to = array($placeholder);
         } else {
           $add_to = $add_cc;
           $add_cc = array();
         }
       }
 
       $add_to = array_unique($add_to);
       $add_cc = array_diff(array_unique($add_cc), $add_to);
 
       $mailer->addTos($add_to);
       if ($add_cc) {
         $mailer->addCCs($add_cc);
       }
     } catch (Exception $ex) {
       $this
         ->setStatus(self::STATUS_FAIL)
         ->setMessage($ex->getMessage())
         ->save();
 
       throw $ex;
     }
 
     try {
       $ok = $mailer->send();
       if (!$ok) {
         // TODO: At some point, we should clean this up and make all mailers
         // throw.
         throw new Exception(
           pht('Mail adapter encountered an unexpected, unspecified failure.'));
       }
 
       $this->setStatus(self::STATUS_SENT);
       $this->save();
 
       return $this;
     } catch (PhabricatorMetaMTAPermanentFailureException $ex) {
       $this
         ->setStatus(self::STATUS_FAIL)
         ->setMessage($ex->getMessage())
         ->save();
 
       throw $ex;
     } catch (Exception $ex) {
       $this
         ->setMessage($ex->getMessage()."\n".$ex->getTraceAsString())
         ->save();
 
       throw $ex;
     }
   }
 
   public static function getReadableStatus($status_code) {
     $readable = array(
       self::STATUS_QUEUE => pht('Queued for Delivery'),
       self::STATUS_FAIL  => pht('Delivery Failed'),
       self::STATUS_SENT  => pht('Sent'),
       self::STATUS_VOID  => pht('Void'),
     );
     $status_code = coalesce($status_code, '?');
     return idx($readable, $status_code, $status_code);
   }
 
   private function generateThreadIndex($seed, $is_first_mail) {
     // When threading, Outlook ignores the 'References' and 'In-Reply-To'
     // headers that most clients use. Instead, it uses a custom 'Thread-Index'
     // header. The format of this header is something like this (from
     // camel-exchange-folder.c in Evolution Exchange):
 
     /* A new post to a folder gets a 27-byte-long thread index. (The value
      * is apparently unique but meaningless.) Each reply to a post gets a
      * 32-byte-long thread index whose first 27 bytes are the same as the
      * parent's thread index. Each reply to any of those gets a
      * 37-byte-long thread index, etc. The Thread-Index header contains a
      * base64 representation of this value.
      */
 
     // The specific implementation uses a 27-byte header for the first email
     // a recipient receives, and a random 5-byte suffix (32 bytes total)
     // thereafter. This means that all the replies are (incorrectly) siblings,
     // but it would be very difficult to keep track of the entire tree and this
     // gets us reasonable client behavior.
 
     $base = substr(md5($seed), 0, 27);
     if (!$is_first_mail) {
       // Not totally sure, but it seems like outlook orders replies by
       // thread-index rather than timestamp, so to get these to show up in the
       // right order we use the time as the last 4 bytes.
       $base .= ' '.pack('N', time());
     }
 
     return base64_encode($base);
   }
 
   public static function shouldMultiplexAllMail() {
     return PhabricatorEnv::getEnvConfig('metamta.one-mail-per-recipient');
   }
 
 
 /* -(  Managing Recipients  )------------------------------------------------ */
 
 
   /**
    * Get all of the recipients for this mail, after preference filters are
    * applied. This list has all objects to whom delivery will be attempted.
    *
    * Note that this expands recipients into their members, because delivery
    * is never directly attempted to aggregate actors like projects.
    *
    * @return  list<phid>  A list of all recipients to whom delivery will be
    *                      attempted.
    * @task recipients
    */
   public function buildRecipientList() {
     $actors = $this->loadAllActors();
     $actors = $this->filterDeliverableActors($actors);
     return mpull($actors, 'getPHID');
   }
 
   public function loadAllActors() {
     $actor_phids = $this->getExpandedRecipientPHIDs();
     return $this->loadActors($actor_phids);
   }
 
   public function getExpandedRecipientPHIDs() {
     $actor_phids = $this->getAllActorPHIDs();
     return $this->expandRecipients($actor_phids);
   }
 
   private function getAllActorPHIDs() {
     return array_merge(
       array($this->getParam('from')),
       $this->getToPHIDs(),
       $this->getCcPHIDs());
   }
 
   /**
    * Expand a list of recipient PHIDs (possibly including aggregate recipients
    * like projects) into a deaggregated list of individual recipient PHIDs.
    * For example, this will expand project PHIDs into a list of the project's
    * members.
    *
    * @param list<phid>  List of recipient PHIDs, possibly including aggregate
    *                    recipients.
    * @return list<phid> Deaggregated list of mailable recipients.
    */
   private function expandRecipients(array $phids) {
     if ($this->recipientExpansionMap === null) {
       $all_phids = $this->getAllActorPHIDs();
       $this->recipientExpansionMap = id(new PhabricatorMetaMTAMemberQuery())
         ->setViewer(PhabricatorUser::getOmnipotentUser())
         ->withPHIDs($all_phids)
         ->execute();
     }
 
     $results = array();
     foreach ($phids as $phid) {
       foreach ($this->recipientExpansionMap[$phid] as $recipient_phid) {
         $results[$recipient_phid] = $recipient_phid;
       }
     }
 
     return array_keys($results);
   }
 
   private function filterDeliverableActors(array $actors) {
     assert_instances_of($actors, 'PhabricatorMetaMTAActor');
     $deliverable_actors = array();
     foreach ($actors as $phid => $actor) {
       if ($actor->isDeliverable()) {
         $deliverable_actors[$phid] = $actor;
       }
     }
     return $deliverable_actors;
   }
 
   private function loadActors(array $actor_phids) {
     $actor_phids = array_filter($actor_phids);
     $viewer = PhabricatorUser::getOmnipotentUser();
 
     $actors = id(new PhabricatorMetaMTAActorQuery())
       ->setViewer($viewer)
       ->withPHIDs($actor_phids)
       ->execute();
 
     if (!$actors) {
       return array();
     }
 
     if ($this->getForceDelivery()) {
       // If we're forcing delivery, skip all the opt-out checks. We don't
       // bother annotating reasoning on the mail in this case because it should
       // always be obvious why the mail hit this rule (e.g., it is a password
       // reset mail).
       foreach ($actors as $actor) {
         $actor->setDeliverable(PhabricatorMetaMTAActor::REASON_FORCE);
       }
       return $actors;
     }
 
     // Exclude explicit recipients.
     foreach ($this->getExcludeMailRecipientPHIDs() as $phid) {
       $actor = idx($actors, $phid);
       if (!$actor) {
         continue;
       }
       $actor->setUndeliverable(PhabricatorMetaMTAActor::REASON_RESPONSE);
     }
 
     // Before running more rules, save a list of the actors who were
     // deliverable before we started running preference-based rules. This stops
     // us from trying to send mail to disabled users just because a Herald rule
     // added them, for example.
     $deliverable = array();
     foreach ($actors as $phid => $actor) {
       if ($actor->isDeliverable()) {
         $deliverable[] = $phid;
       }
     }
 
     // For the rest of the rules, order matters. We're going to run all the
     // possible rules in order from weakest to strongest, and let the strongest
     // matching rule win. The weaker rules leave annotations behind which help
     // users understand why the mail was routed the way it was.
 
     // Exclude the actor if their preferences are set.
     $from_phid = $this->getParam('from');
     $from_actor = idx($actors, $from_phid);
     if ($from_actor) {
       $from_user = id(new PhabricatorPeopleQuery())
         ->setViewer($viewer)
         ->withPHIDs(array($from_phid))
         ->execute();
       $from_user = head($from_user);
       if ($from_user) {
         $pref_key = PhabricatorUserPreferences::PREFERENCE_NO_SELF_MAIL;
         $exclude_self = $from_user
           ->loadPreferences()
           ->getPreference($pref_key);
         if ($exclude_self) {
           $from_actor->setUndeliverable(PhabricatorMetaMTAActor::REASON_SELF);
         }
       }
     }
 
     $all_prefs = id(new PhabricatorUserPreferences())->loadAllWhere(
       'userPHID in (%Ls)',
       $actor_phids);
     $all_prefs = mpull($all_prefs, null, 'getUserPHID');
 
     $value_email = PhabricatorUserPreferences::MAILTAG_PREFERENCE_EMAIL;
 
     // Exclude all recipients who have set preferences to not receive this type
     // of email (for example, a user who says they don't want emails about task
     // CC changes).
     $tags = $this->getParam('mailtags');
     if ($tags) {
       foreach ($all_prefs as $phid => $prefs) {
         $user_mailtags = $prefs->getPreference(
           PhabricatorUserPreferences::PREFERENCE_MAILTAGS,
           array());
 
         // The user must have elected to receive mail for at least one
         // of the mailtags.
         $send = false;
         foreach ($tags as $tag) {
           if (((int)idx($user_mailtags, $tag, $value_email)) == $value_email) {
             $send = true;
             break;
           }
         }
 
         if (!$send) {
           $actors[$phid]->setUndeliverable(
             PhabricatorMetaMTAActor::REASON_MAILTAGS);
         }
       }
     }
 
     // If recipients were initially deliverable and were added by "Send me an
     // email" Herald rules, annotate them as such and make them deliverable
     // again, overriding any changes made by the  "self mail" and "mail tags"
     // settings.
     $force_recipients = $this->getForceHeraldMailRecipientPHIDs();
     $force_recipients = array_fuse($force_recipients);
     if ($force_recipients) {
       foreach ($deliverable as $phid) {
         if (isset($force_recipients[$phid])) {
           $actors[$phid]->setDeliverable(
             PhabricatorMetaMTAActor::REASON_FORCE_HERALD);
         }
       }
     }
 
     // Exclude recipients who don't want any mail. This rule is very strong
     // and runs last.
     foreach ($all_prefs as $phid => $prefs) {
       $exclude = $prefs->getPreference(
         PhabricatorUserPreferences::PREFERENCE_NO_MAIL,
         false);
       if ($exclude) {
         $actors[$phid]->setUndeliverable(
           PhabricatorMetaMTAActor::REASON_MAIL_DISABLED);
       }
     }
 
     return $actors;
   }
 
   private function shouldRateLimitMail(array $all_recipients) {
     try {
       PhabricatorSystemActionEngine::willTakeAction(
         $all_recipients,
         new PhabricatorMetaMTAErrorMailAction(),
         1);
       return false;
     } catch (PhabricatorSystemActionRateLimitException $ex) {
       return true;
     }
   }
 
   public function delete() {
     $this->openTransaction();
       queryfx(
         $this->establishConnection('w'),
         'DELETE FROM %T WHERE src = %s AND type = %d',
         PhabricatorEdgeConfig::TABLE_NAME_EDGE,
         $this->getPHID(),
         PhabricatorMetaMTAMailHasRecipientEdgeType::EDGECONST);
       $ret = parent::delete();
     $this->saveTransaction();
 
     return $ret;
   }
 
+  public function generateHeaders() {
+    $headers = array();
+
+    $headers[] = array('X-Phabricator-Sent-This-Message', 'Yes');
+    $headers[] = array('X-Mail-Transport-Agent', 'MetaMTA');
+
+    // Some clients respect this to suppress OOF and other auto-responses.
+    $headers[] = array('X-Auto-Response-Suppress', 'All');
+
+    // If the message has mailtags, filter out any recipients who don't want
+    // to receive this type of mail.
+    $mailtags = $this->getParam('mailtags');
+    if ($mailtags) {
+      $tag_header = array();
+      foreach ($mailtags as $mailtag) {
+        $tag_header[] = '<'.$mailtag.'>';
+      }
+      $tag_header = implode(', ', $tag_header);
+      $headers[] = array('X-Phabricator-Mail-Tags', $tag_header);
+    }
+
+    $value = $this->getParam('headers', array());
+    foreach ($value as $pair) {
+      list($header_key, $header_value) = $pair;
+
+      // NOTE: If we have \n in a header, SES rejects the email.
+      $header_value = str_replace("\n", ' ', $header_value);
+      $headers[] = array($header_key, $header_value);
+    }
+
+    $is_bulk = $this->getParam('is-bulk');
+    if ($is_bulk) {
+      $headers[] = array('Precedence', 'bulk');
+    }
+
+    return $headers;
+  }
+
+  public function getDeliveredHeaders() {
+    return $this->getParam('headers.sent');
+  }
+
+  public function getDeliveredActors() {
+    return $this->getParam('actors.sent');
+  }
+
 
 /* -(  PhabricatorPolicyInterface  )----------------------------------------- */
 
 
   public function getCapabilities() {
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,
     );
   }
 
   public function getPolicy($capability) {
     return PhabricatorPolicies::POLICY_NOONE;
   }
 
   public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
     $actor_phids = $this->getExpandedRecipientPHIDs();
     return in_array($viewer->getPHID(), $actor_phids);
   }
 
   public function describeAutomaticCapability($capability) {
     return pht(
       'The mail sender and message recipients can always see the mail.');
   }
 
 
 }