diff --git a/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerAdapter.php b/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerAdapter.php
--- a/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerAdapter.php
+++ b/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerAdapter.php
@@ -12,6 +12,7 @@
     require_once $root.'/externals/phpmailer/class.phpmailer.php';
     $this->mailer = new PHPMailer($use_exceptions = true);
     $this->mailer->CharSet = 'utf-8';
+    $this->mailer->Encoding = 'quoted-printable';
 
     // By default, PHPMailer sends one mail per recipient. We handle
     // multiplexing higher in the stack, so tell it to send mail exactly
@@ -102,6 +103,11 @@
     return $this;
   }
 
+  public function setSender($sender) {
+    $this->addHeader('List-Id', $sender);
+    return $this;
+  }
+
   public function setSubject($subject) {
     $this->mailer->Subject = $subject;
     return $this;
diff --git a/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerLiteAdapter.php b/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerLiteAdapter.php
--- a/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerLiteAdapter.php
+++ b/src/applications/metamta/adapter/PhabricatorMailImplementationPHPMailerLiteAdapter.php
@@ -31,6 +31,12 @@
     return $this;
   }
 
+  public function setSender($sender) {
+    $this->mailer->Sender = $sender;
+    $this->mailer->AddCustomHeader('List-Id:'.$sender);
+    return $this;
+  }
+
   public function addReplyTo($email, $name = '') {
     $this->mailer->AddReplyTo($email, $name);
     return $this;
diff --git a/src/applications/metamta/adapter/PhabricatorMailImplementationSendGridAdapter.php b/src/applications/metamta/adapter/PhabricatorMailImplementationSendGridAdapter.php
--- a/src/applications/metamta/adapter/PhabricatorMailImplementationSendGridAdapter.php
+++ b/src/applications/metamta/adapter/PhabricatorMailImplementationSendGridAdapter.php
@@ -51,6 +51,11 @@
     return $this;
   }
 
+  public function setSender($sender) {
+    $this->addHeader('List-Id', $sender);
+    return $this;
+  }
+
   public function setBody($body) {
     $this->params['body'] = $body;
     return $this;
diff --git a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
--- a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
+++ b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
@@ -419,6 +419,7 @@
 
             if ($can_send_as_user) {
               $mailer->setFrom($actor_email, $actor_name);
+              $mailer->setSender($default_from);
             } else {
               $from_email = coalesce($actor_email, $default_from);
               $from_name = coalesce($actor_name, pht('Phabricator'));