diff --git a/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php b/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
index c7fde5f6e4..b789fe57d0 100644
--- a/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
+++ b/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
@@ -1,248 +1,252 @@
 <?php
 
 final class PhabricatorExtraConfigSetupCheck extends PhabricatorSetupCheck {
 
   public function getDefaultGroup() {
     return self::GROUP_OTHER;
   }
 
   protected function executeChecks() {
     $ancient_config = self::getAncientConfig();
 
     $all_keys = PhabricatorEnv::getAllConfigKeys();
     $all_keys = array_keys($all_keys);
     sort($all_keys);
 
     $defined_keys = PhabricatorApplicationConfigOptions::loadAllOptions();
 
     foreach ($all_keys as $key) {
       if (isset($defined_keys[$key])) {
         continue;
       }
 
       if (isset($ancient_config[$key])) {
         $summary = pht(
           'This option has been removed. You may delete it at your '.
           'convenience.');
         $message = pht(
           "The configuration option '%s' has been removed. You may delete ".
           "it at your convenience.".
           "\n\n%s",
           $key,
           $ancient_config[$key]);
         $short = pht('Obsolete Config');
         $name = pht('Obsolete Configuration Option "%s"', $key);
       } else {
         $summary = pht('This option is not recognized. It may be misspelled.');
         $message = pht(
           "The configuration option '%s' is not recognized. It may be ".
           "misspelled, or it might have existed in an older version of ".
           "Phabricator. It has no effect, and should be corrected or deleted.",
           $key);
         $short = pht('Unknown Config');
         $name = pht('Unknown Configuration Option "%s"', $key);
       }
 
       $issue = $this->newIssue('config.unknown.'.$key)
         ->setShortName($short)
         ->setName($name)
         ->setSummary($summary);
 
       $stack = PhabricatorEnv::getConfigSourceStack();
       $stack = $stack->getStack();
 
       $found = array();
       $found_local = false;
       $found_database = false;
 
       foreach ($stack as $source_key => $source) {
         $value = $source->getKeys(array($key));
         if ($value) {
           $found[] = $source->getName();
           if ($source instanceof PhabricatorConfigDatabaseSource) {
             $found_database = true;
           }
           if ($source instanceof PhabricatorConfigLocalSource) {
             $found_local = true;
           }
         }
       }
 
       $message = $message."\n\n".pht(
         'This configuration value is defined in these %d '.
         'configuration source(s): %s.',
         count($found),
         implode(', ', $found));
       $issue->setMessage($message);
 
       if ($found_local) {
         $command = csprintf('phabricator/ $ ./bin/config delete %s', $key);
         $issue->addCommand($command);
       }
 
       if ($found_database) {
         $issue->addPhabricatorConfig($key);
       }
     }
   }
 
   /**
    * Return a map of deleted config options. Keys are option keys; values are
    * explanations of what happened to the option.
    */
   public static function getAncientConfig() {
     $reason_auth = pht(
       'This option has been migrated to the "Auth" application. Your old '.
       'configuration is still in effect, but now stored in "Auth" instead of '.
       'configuration. Going forward, you can manage authentication from '.
       'the web UI.');
 
     $auth_config = array(
       'controller.oauth-registration',
       'auth.password-auth-enabled',
       'facebook.auth-enabled',
       'facebook.registration-enabled',
       'facebook.auth-permanent',
       'facebook.application-id',
       'facebook.application-secret',
       'facebook.require-https-auth',
       'github.auth-enabled',
       'github.registration-enabled',
       'github.auth-permanent',
       'github.application-id',
       'github.application-secret',
       'google.auth-enabled',
       'google.registration-enabled',
       'google.auth-permanent',
       'google.application-id',
       'google.application-secret',
       'ldap.auth-enabled',
       'ldap.hostname',
       'ldap.port',
       'ldap.base_dn',
       'ldap.search_attribute',
       'ldap.search-first',
       'ldap.username-attribute',
       'ldap.real_name_attributes',
       'ldap.activedirectory_domain',
       'ldap.version',
       'ldap.referrals',
       'ldap.anonymous-user-name',
       'ldap.anonymous-user-password',
       'ldap.start-tls',
       'disqus.auth-enabled',
       'disqus.registration-enabled',
       'disqus.auth-permanent',
       'disqus.application-id',
       'disqus.application-secret',
       'phabricator.oauth-uri',
       'phabricator.auth-enabled',
       'phabricator.registration-enabled',
       'phabricator.auth-permanent',
       'phabricator.application-id',
       'phabricator.application-secret',
     );
 
     $ancient_config = array_fill_keys($auth_config, $reason_auth);
 
     $markup_reason = pht(
       'Custom remarkup rules are now added by subclassing '.
       'PhabricatorRemarkupCustomInlineRule or '.
       'PhabricatorRemarkupCustomBlockRule.');
 
     $session_reason = pht(
       'Sessions now expire and are garbage collected rather than having an '.
       'arbitrary concurrency limit.');
 
     $differential_field_reason = pht(
       'All Differential fields are now managed through the configuration '.
       'option "%s". Use that option to configure which fields are shown.',
       'differential.fields');
 
     $reply_domain_reason = pht(
       'Individual application reply handler domains have been removed. '.
       'Configure a reply domain with "%s".',
       'metamta.reply-handler-domain');
 
     $reply_handler_reason = pht(
       'Reply handlers can no longer be overridden with configuration.');
 
     $ancient_config += array(
       'phid.external-loaders' =>
         pht(
           'External loaders have been replaced. Extend `PhabricatorPHIDType` '.
           'to implement new PHID and handle types.'),
       'maniphest.custom-task-extensions-class' =>
         pht(
           'Maniphest fields are now loaded automatically. You can configure '.
           'them with `maniphest.fields`.'),
       'maniphest.custom-fields' =>
         pht(
           'Maniphest fields are now defined in '.
           '`maniphest.custom-field-definitions`. Existing definitions have '.
           'been migrated.'),
       'differential.custom-remarkup-rules' => $markup_reason,
       'differential.custom-remarkup-block-rules' => $markup_reason,
       'auth.sshkeys.enabled' => pht(
         'SSH keys are now actually useful, so they are always enabled.'),
       'differential.anonymous-access' => pht(
         'Phabricator now has meaningful global access controls. See '.
         '`policy.allow-public`.'),
       'celerity.resource-path' => pht(
         'An alternate resource map is no longer supported. Instead, use '.
         'multiple maps. See T4222.'),
       'metamta.send-immediately' => pht(
         'Mail is now always delivered by the daemons.'),
       'auth.sessions.conduit' => $session_reason,
       'auth.sessions.web' => $session_reason,
       'tokenizer.ondemand' => pht(
         'Phabricator now manages typeahead strategies automatically.'),
       'differential.revision-custom-detail-renderer' => pht(
         'Obsolete; use standard rendering events instead.'),
       'differential.show-host-field' => $differential_field_reason,
       'differential.show-test-plan-field' => $differential_field_reason,
       'differential.field-selector' => $differential_field_reason,
       'phabricator.show-beta-applications' => pht(
         'This option has been renamed to `phabricator.show-prototypes` '.
         'to emphasize the unfinished nature of many prototype applications. '.
         'Your existing setting has been migrated.'),
       'notification.user' => pht(
         'The notification server no longer requires root permissions. Start '.
         'the server as the user you want it to run under.'),
       'notification.debug' => pht(
         'Notifications no longer have a dedicated debugging mode.'),
       'translation.provider' => pht(
         'The translation implementation has changed and providers are no '.
         'longer used or supported.'),
       'config.mask' => pht(
         'Use `config.hide` instead of this option.'),
       'phd.start-taskmasters' => pht(
         'Taskmasters now use an autoscaling pool. You can configure the '.
         'pool size with `phd.taskmasters`.'),
       'storage.engine-selector' => pht(
         'Phabricator now automatically discovers available storage engines '.
         'at runtime.'),
       'storage.upload-size-limit' => pht(
         'Phabricator now supports arbitrarily large files. Consult the '.
         'documentation for configuration details.'),
       'security.allow-outbound-http' => pht(
         'This option has been replaced with the more granular option '.
         '`security.outbound-blacklist`.'),
       'metamta.reply.show-hints' => pht(
         'Phabricator no longer shows reply hints in mail.'),
 
       'metamta.differential.reply-handler-domain' => $reply_domain_reason,
       'metamta.diffusion.reply-handler-domain' => $reply_domain_reason,
       'metamta.macro.reply-handler-domain' => $reply_domain_reason,
       'metamta.maniphest.reply-handler-domain' => $reply_domain_reason,
       'metamta.pholio.reply-handler-domain' => $reply_domain_reason,
 
       'metamta.diffusion.reply-handler' => $reply_handler_reason,
       'metamta.differential.reply-handler' => $reply_handler_reason,
       'metamta.maniphest.reply-handler' => $reply_handler_reason,
       'metamta.package.reply-handler' => $reply_handler_reason,
+
+      'metamta.precedence-bulk' => pht(
+        'Phabricator now always sends transaction mail with '.
+        '"Precedence: bulk" to improve deliverability.'),
     );
 
     return $ancient_config;
   }
 }
diff --git a/src/applications/config/option/PhabricatorMetaMTAConfigOptions.php b/src/applications/config/option/PhabricatorMetaMTAConfigOptions.php
index 1bc8d21bdb..bbd58e0d51 100644
--- a/src/applications/config/option/PhabricatorMetaMTAConfigOptions.php
+++ b/src/applications/config/option/PhabricatorMetaMTAConfigOptions.php
@@ -1,352 +1,344 @@
 <?php
 
 final class PhabricatorMetaMTAConfigOptions
   extends PhabricatorApplicationConfigOptions {
 
   public function getName() {
     return pht('Mail');
   }
 
   public function getDescription() {
     return pht('Configure Mail.');
   }
 
   public function getFontIcon() {
     return 'fa-send';
   }
 
   public function getGroup() {
     return 'core';
   }
 
   public function getOptions() {
     $send_as_user_desc = $this->deformat(pht(<<<EODOC
 When a user takes an action which generates an email notification (like
 commenting on a Differential revision), Phabricator can either send that mail
 "From" the user's email address (like "alincoln@logcabin.com") or "From" the
 'metamta.default-address' address.
 
 The user experience is generally better if Phabricator uses the user's real
 address as the "From" since the messages are easier to organize when they appear
 in mail clients, but this will only work if the server is authorized to send
 email on behalf of the "From" domain. Practically, this means:
 
   - If you are doing an install for Example Corp and all the users will have
     corporate @corp.example.com addresses and any hosts Phabricator is running
     on are authorized to send email from corp.example.com, you can enable this
     to make the user experience a little better.
   - If you are doing an install for an open source project and your users will
     be registering via Facebook and using personal email addresses, you probably
     should not enable this or all of your outgoing email might vanish into SFP
     blackholes.
   - If your install is anything else, you're safer leaving this off, at least
     initially, since the risk in turning it on is that your outgoing mail will
     never arrive.
 EODOC
 ));
 
     $one_mail_per_recipient_desc = $this->deformat(pht(<<<EODOC
 When a message is sent to multiple recipients (for example, several reviewers on
 a code review), Phabricator can either deliver one email to everyone (e.g., "To:
 alincoln, usgrant, htaft") or separate emails to each user (e.g., "To:
 alincoln", "To: usgrant", "To: htaft"). The major advantages and disadvantages
 of each approach are:
 
   - One mail to everyone:
     - Recipients can see To/Cc at a glance.
     - If you use mailing lists, you won't get duplicate mail if you're
       a normal recipient and also Cc'd on a mailing list.
     - Getting threading to work properly is harder, and probably requires
       making mail less useful by turning off options.
     - Sometimes people will "Reply All" and everyone will get two mails,
       one from the user and one from Phabricator turning their mail into
       a comment.
     - Not supported with a private reply-to address.
     - Mails are sent in the server default translation.
   - One mail to each user:
     - Recipients need to look in the mail body to see To/Cc.
     - If you use mailing lists, recipients may sometimes get duplicate
       mail.
     - Getting threading to work properly is easier, and threading settings
       can be customzied by each user.
     - "Reply All" no longer spams all other users.
     - Required if private reply-to addresses are configured.
     - Mails are sent in the language of user preference.
 
 In the code, splitting one outbound email into one-per-recipient is sometimes
 referred to as "multiplexing".
 EODOC
 ));
 
     $herald_hints_description = $this->deformat(pht(<<<EODOC
 You can disable the Herald hints in email if users prefer smaller messages.
 These are the links under the header "WHY DID I GET THIS EMAIL?". If you set
 this to true, they will not appear in any mail. Users can still navigate to
 the links via the web interface.
 EODOC
 ));
 
     $reply_hints_description = $this->deformat(pht(<<<EODOC
 You can disable the hints under "REPLY HANDLER ACTIONS" if users prefer
 smaller messages. The actions themselves will still work properly.
 EODOC
 ));
 
     $recipient_hints_description = $this->deformat(pht(<<<EODOC
 You can disable the "To:" and "Cc:" footers in mail if users prefer smaller
 messages.
 EODOC
 ));
 
     $bulk_description = $this->deformat(pht(<<<EODOC
 If this option is enabled, Phabricator will add a "Precedence: bulk" header to
 transactional mail (e.g., Differential, Maniphest and Herald notifications).
 This may improve the behavior of some auto-responder software and prevent it
 from replying. However, it may also cause deliverability issues -- notably, you
 currently can not send this header via Amazon SES, and enabling this option with
 SES will prevent delivery of any affected mail.
 EODOC
 ));
 
     $email_preferences_description = $this->deformat(pht(<<<EODOC
 You can disable the email preference link in emails if users prefer smaller
 emails.
 EODOC
 ));
 
     $re_prefix_description = $this->deformat(pht(<<<EODOC
 Mail.app on OS X Lion won't respect threading headers unless the subject is
 prefixed with "Re:". If you enable this option, Phabricator will add "Re:" to
 the subject line of all mail which is expected to thread. If you've set
 'metamta.one-mail-per-recipient', users can override this setting in their
 preferences.
 EODOC
 ));
 
     $vary_subjects_description = $this->deformat(pht(<<<EODOC
 If true, allow MetaMTA to change mail subjects to put text like '[Accepted]' and
 '[Commented]' in them. This makes subjects more useful, but might break
 threading on some clients. If you've set 'metamta.one-mail-per-recipient', users
 can override this setting in their preferences.
 EODOC
 ));
 
     $reply_to_description = $this->deformat(pht(<<<EODOC
 If you enable {{metamta.public-replies}}, Phabricator uses "From" to
 authenticate users. You can additionally enable this setting to try to
 authenticate with 'Reply-To'. Note that this is completely spoofable and
 insecure (any user can set any 'Reply-To' address) but depending on the nature
 of your install or other deliverability conditions this might be okay.
 Generally, you can't do much more by spoofing Reply-To than be annoying (you can
 write but not read content). But this is still **COMPLETELY INSECURE**.
 EODOC
 ));
 
     $adapter_description = $this->deformat(pht(<<<EODOC
 Adapter class to use to transmit mail to the MTA. The default uses
 PHPMailerLite, which will invoke "sendmail". This is appropriate if sendmail
 actually works on your host, but if you haven't configured mail it may not be so
 great. A number of other mailers are available (e.g., SES, SendGrid, SMTP,
 custom mailers), consult "Configuring Outbound Email" in the documentation for
 details.
 EODOC
 ));
 
     $placeholder_description = $this->deformat(pht(<<<EODOC
 When sending a message that has no To recipient (i.e. all recipients are CC'd,
 for example when multiplexing mail), set the To field to the following value. If
 no value is set, messages with no To will have their CCs upgraded to To.
 EODOC
 ));
 
     $public_replies_description = $this->deformat(pht(<<<EODOC
 By default, Phabricator generates unique reply-to addresses and sends a separate
 email to each recipient when you enable reply handling. This is more secure than
 using "From" to establish user identity, but can mean users may receive multiple
 emails when they are on mailing lists. Instead, you can use a single, non-unique
 reply to address and authenticate users based on the "From" address by setting
 this to 'true'. This trades away a little bit of security for convenience, but
 it's reasonable in many installs. Object interactions are still protected using
 hashes in the single public email address, so objects can not be replied to
 blindly.
 EODOC
 ));
 
     $single_description = $this->deformat(pht(<<<EODOC
 If you want to use a single mailbox for Phabricator reply mail, you can use this
 and set a common prefix for reply addresses generated by Phabricator. It will
 make use of the fact that a mail-address such as
 `phabricator+D123+1hjk213h@example.com` will be delivered to the `phabricator`
 user's mailbox. Set this to the left part of the email address and it will be
 prepended to all generated reply addresses.
 
 For example, if you want to use `phabricator@example.com`, this should be set
 to `phabricator`.
 EODOC
 ));
 
     $address_description = $this->deformat(pht(<<<EODOC
 When email is sent, what format should Phabricator use for user's email
 addresses? Valid values are:
 
  - `short`: 'gwashington <gwashington@example.com>'
  - `real`:  'George Washington <gwashington@example.com>'
  - `full`: 'gwashington (George Washington) <gwashington@example.com>'
 
 The default is `full`.
 EODOC
 ));
 
     return array(
       $this->newOption(
         'metamta.default-address',
         'string',
         'noreply@phabricator.example.com')
         ->setDescription(pht('Default "From" address.')),
       $this->newOption(
         'metamta.domain',
         'string',
         'phabricator.example.com')
         ->setDescription(pht('Domain used to generate Message-IDs.')),
       $this->newOption(
         'metamta.mail-adapter',
         'class',
         'PhabricatorMailImplementationPHPMailerLiteAdapter')
         ->setBaseClass('PhabricatorMailImplementationAdapter')
         ->setSummary(pht('Control how mail is sent.'))
         ->setDescription($adapter_description),
       $this->newOption(
         'metamta.one-mail-per-recipient',
         'bool',
         true)
         ->setBoolOptions(
           array(
             pht('Send Mail To Each Recipient'),
             pht('Send Mail To All Recipients'),
           ))
         ->setSummary(
           pht(
             'Controls whether Phabricator sends one email with multiple '.
             'recipients in the "To:" line, or multiple emails, each with a '.
             'single recipient in the "To:" line.'))
         ->setDescription($one_mail_per_recipient_desc),
       $this->newOption('metamta.can-send-as-user', 'bool', false)
         ->setBoolOptions(
           array(
             pht('Send as User Taking Action'),
             pht('Send as Phabricator'),
           ))
         ->setSummary(
           pht(
             'Controls whether Phabricator sends email "From" users.'))
         ->setDescription($send_as_user_desc),
       $this->newOption(
         'metamta.reply-handler-domain',
         'string',
         null)
         ->setLocked(true)
         ->setDescription(pht('Domain used for reply email addresses.'))
         ->addExample('phabricator.example.com', ''),
       $this->newOption('metamta.herald.show-hints', 'bool', true)
         ->setBoolOptions(
           array(
             pht('Show Herald Hints'),
             pht('No Herald Hints'),
           ))
         ->setSummary(pht('Show hints about Herald rules in email.'))
         ->setDescription($herald_hints_description),
       $this->newOption('metamta.recipients.show-hints', 'bool', true)
         ->setBoolOptions(
           array(
             pht('Show Recipient Hints'),
             pht('No Recipient Hints'),
           ))
         ->setSummary(pht('Show "To:" and "Cc:" footer hints in email.'))
         ->setDescription($recipient_hints_description),
       $this->newOption('metamta.email-preferences', 'bool', true)
         ->setBoolOptions(
           array(
             pht('Show Email Preferences Link'),
             pht('No Email Preferences Link'),
           ))
         ->setSummary(pht('Show email preferences link in email.'))
         ->setDescription($email_preferences_description),
-      $this->newOption('metamta.precedence-bulk', 'bool', false)
-        ->setBoolOptions(
-          array(
-            pht('Add "Precedence: bulk" Header'),
-            pht('No "Precedence: bulk" Header'),
-          ))
-        ->setSummary(pht('Control the "Precedence: bulk" header.'))
-        ->setDescription($bulk_description),
       $this->newOption('metamta.re-prefix', 'bool', false)
         ->setBoolOptions(
           array(
             pht('Force "Re:" Subject Prefix'),
             pht('No "Re:" Subject Prefix'),
           ))
         ->setSummary(pht('Control "Re:" subject prefix, for Mail.app.'))
         ->setDescription($re_prefix_description),
       $this->newOption('metamta.vary-subjects', 'bool', true)
         ->setBoolOptions(
           array(
             pht('Allow Varied Subjects'),
             pht('Always Use the Same Thread Subject'),
           ))
         ->setSummary(pht('Control subject variance, for some mail clients.'))
         ->setDescription($vary_subjects_description),
       $this->newOption('metamta.insecure-auth-with-reply-to', 'bool', false)
         ->setBoolOptions(
           array(
             pht('Allow Insecure Reply-To Auth'),
             pht('Disallow Reply-To Auth'),
           ))
         ->setSummary(pht('Trust "Reply-To" headers for authentication.'))
         ->setDescription($reply_to_description),
       $this->newOption('metamta.placeholder-to-recipient', 'string', null)
         ->setSummary(pht('Placeholder for mail with only CCs.'))
         ->setDescription($placeholder_description),
       $this->newOption('metamta.public-replies', 'bool', false)
         ->setBoolOptions(
           array(
             pht('Use Public Replies (Less Secure)'),
             pht('Use Private Replies (More Secure)'),
           ))
         ->setSummary(
           pht(
             'Phabricator can use less-secure but mailing list friendly public '.
             'reply addresses.'))
         ->setDescription($public_replies_description),
       $this->newOption('metamta.single-reply-handler-prefix', 'string', null)
         ->setSummary(
           pht('Allow Phabricator to use a single mailbox for all replies.'))
         ->setDescription($single_description),
       $this->newOption('metamta.user-address-format', 'enum', 'full')
         ->setEnumOptions(
           array(
             'short' => 'short',
             'real' => 'real',
             'full' => 'full',
           ))
         ->setSummary(pht('Control how Phabricator renders user names in mail.'))
         ->setDescription($address_description)
         ->addExample('gwashington <gwashington@example.com>', 'short')
         ->addExample('George Washington <gwashington@example.com>', 'real')
         ->addExample(
           'gwashington (George Washington) <gwashington@example.com>',
           'full'),
       $this->newOption('metamta.email-body-limit', 'int', 524288)
         ->setDescription(
           pht(
             'You can set a limit for the maximum byte size of outbound mail. '.
             'Mail which is larger than this limit will be truncated before '.
             'being sent. This can be useful if your MTA rejects mail which '.
             'exceeds some limit (this is reasonably common). Specify a value '.
             'in bytes.'))
         ->setSummary(pht('Global cap for size of generated emails (bytes).'))
         ->addExample(524288, pht('Truncate at 512KB'))
         ->addExample(1048576, pht('Truncate at 1MB')),
     );
   }
 
 }
diff --git a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
index 4f2fe4821f..7bf19a935a 100644
--- a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
+++ b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
@@ -1,966 +1,964 @@
 <?php
 
 /**
  * @task recipients   Managing Recipients
  */
 final class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
 
   const STATUS_QUEUE = 'queued';
   const STATUS_SENT  = 'sent';
   const STATUS_FAIL  = 'fail';
   const STATUS_VOID  = 'void';
 
   const RETRY_DELAY   = 5;
 
   protected $parameters;
   protected $status;
   protected $message;
   protected $relatedPHID;
 
   private $recipientExpansionMap;
 
   public function __construct() {
 
     $this->status     = self::STATUS_QUEUE;
     $this->parameters = array();
 
     parent::__construct();
   }
 
   protected function getConfiguration() {
     return array(
       self::CONFIG_SERIALIZATION => array(
         'parameters'  => self::SERIALIZATION_JSON,
       ),
       self::CONFIG_COLUMN_SCHEMA => array(
         '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'),
         ),
         'relatedPHID' => array(
           'columns' => array('relatedPHID'),
         ),
         'key_created' => array(
           'columns' => array('dateCreated'),
         ),
       ),
     ) + parent::getConfiguration();
   }
 
   protected function setParam($param, $value) {
     $this->parameters[$param] = $value;
     return $this;
   }
 
   protected function getParam($param, $default = null) {
     return idx($this->parameters, $param, $default);
   }
 
   /**
    * Set tags (@{class:MetaMTANotificationType} constants) which identify the
    * content of this mail in a general way. 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> List of @{class:MetaMTANotificationType} constants.
    * @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 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 $phids) {
     foreach ($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);
     return $this;
   }
 
   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 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 task ID.
       $result = parent::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('Trying to send an already-sent mail!');
       }
     }
 
     try {
       $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) {
-              if (PhabricatorEnv::getEnvConfig('metamta.precedence-bulk')) {
-                $mailer->addHeader('Precedence', 'bulk');
-              }
+              $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);
             } 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);
             }
             $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.
             break;
           default:
             // Just discard.
         }
       }
 
       $body = idx($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']);
       }
 
       if (!$add_to && !$add_cc) {
         $this->setStatus(self::STATUS_VOID);
         $this->setMessage(
           '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 `phabricator.silent` '.
             'in the configuration to change this setting.'));
         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) {
     static $readable = array(
       self::STATUS_QUEUE => 'Queued for Delivery',
       self::STATUS_FAIL  => 'Delivery Failed',
       self::STATUS_SENT  => 'Sent',
       self::STATUS_VOID  => '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->getAllActorPHIDs();
     $actor_phids = $this->expandRecipients($actor_phids);
     return $this->loadActors($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.
       return $actors;
     }
 
     // Exclude explicit recipients.
     foreach ($this->getExcludeMailRecipientPHIDs() as $phid) {
       $actor = idx($actors, $phid);
       if (!$actor) {
         continue;
       }
       $actor->setUndeliverable(
         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).'));
     }
 
     // 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(
             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).'));
         }
       }
     }
 
     $all_prefs = id(new PhabricatorUserPreferences())->loadAllWhere(
       'userPHID in (%Ls)',
       $actor_phids);
     $all_prefs = mpull($all_prefs, null, 'getUserPHID');
 
     // Exclude recipients who don't want any mail.
     foreach ($all_prefs as $phid => $prefs) {
       $exclude = $prefs->getPreference(
         PhabricatorUserPreferences::PREFERENCE_NO_MAIL,
         false);
       if ($exclude) {
         $actors[$phid]->setUndeliverable(
           pht(
             'This recipient has disabled all email notifications '.
             '(Settings > Email Preferences > Email Notifications).'));
       }
     }
 
     $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(
             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).'));
         }
       }
     }
 
     return $actors;
   }
 
   private function shouldRateLimitMail(array $all_recipients) {
     try {
       PhabricatorSystemActionEngine::willTakeAction(
         $all_recipients,
         new PhabricatorMetaMTAErrorMailAction(),
         1);
       return false;
     } catch (PhabricatorSystemActionRateLimitException $ex) {
       return true;
     }
   }
 
 
 }