diff --git a/conf/default.conf.php b/conf/default.conf.php
index 9c973f6f13..c287485432 100644
--- a/conf/default.conf.php
+++ b/conf/default.conf.php
@@ -279,6 +279,15 @@ return array(
   // address will be stored in an 'From Email' field on the task.
   'metamta.maniphest.default-public-author' => null,
 
+  // 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.
+  'metamta.precedence-bulk' => false,
+
 
 // -- Auth ------------------------------------------------------------------ //
 
diff --git a/src/applications/differential/mail/base/DifferentialMail.php b/src/applications/differential/mail/base/DifferentialMail.php
index ea898bed4c..c298f533c3 100644
--- a/src/applications/differential/mail/base/DifferentialMail.php
+++ b/src/applications/differential/mail/base/DifferentialMail.php
@@ -106,6 +106,7 @@ abstract class DifferentialMail {
       $template->addHeader('X-Herald-Rules', $this->heraldRulesHeader);
     }
 
+    $template->setIsBulk(true);
     $template->setRelatedPHID($this->getRevision()->getPHID());
 
     $phids = array();
diff --git a/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php b/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php
index c43f85ed39..1674a31f61 100644
--- a/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php
+++ b/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php
@@ -254,6 +254,7 @@ class ManiphestTransactionEditor {
       ->addHeader('Thread-Topic', 'Maniphest Task '.$task->getID())
       ->setThreadID($thread_id, $is_create)
       ->setRelatedPHID($task->getPHID())
+      ->setIsBulk(true)
       ->setBody($body);
 
     $mails = $reply_handler->multiplexMail(
diff --git a/src/applications/metamta/controller/send/PhabricatorMetaMTASendController.php b/src/applications/metamta/controller/send/PhabricatorMetaMTASendController.php
index 8b971b878f..0f865d7928 100644
--- a/src/applications/metamta/controller/send/PhabricatorMetaMTASendController.php
+++ b/src/applications/metamta/controller/send/PhabricatorMetaMTASendController.php
@@ -32,6 +32,7 @@ class PhabricatorMetaMTASendController extends PhabricatorMetaMTAController {
       $mail->setFrom($request->getUser()->getPHID());
       $mail->setSimulatedFailureCount($request->getInt('failures'));
       $mail->setIsHTML($request->getInt('html'));
+      $mail->setIsBulk($request->getInt('bulk'));
       $mail->save();
       if ($request->getInt('immediately')) {
         $mail->sendNow();
@@ -110,6 +111,10 @@ class PhabricatorMetaMTASendController extends PhabricatorMetaMTAController {
         id(new AphrontFormCheckboxControl())
           ->setLabel('HTML')
           ->addCheckbox('html', '1', 'Send as HTML email.'))
+      ->appendChild(
+        id(new AphrontFormCheckboxControl())
+          ->setLabel('Bulk')
+          ->addCheckbox('bulk', '1', 'Send with bulk email headers.'))
       ->appendChild(
         id(new AphrontFormCheckboxControl())
           ->setLabel('Send Now')
diff --git a/src/applications/metamta/storage/mail/PhabricatorMetaMTAMail.php b/src/applications/metamta/storage/mail/PhabricatorMetaMTAMail.php
index c8f59a91b3..0ffd7017e1 100644
--- a/src/applications/metamta/storage/mail/PhabricatorMetaMTAMail.php
+++ b/src/applications/metamta/storage/mail/PhabricatorMetaMTAMail.php
@@ -151,6 +151,20 @@ class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
     return $this;
   }
 
+  /**
+   * 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
@@ -315,6 +329,13 @@ class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
               $mailer->setIsHTML(true);
             }
             break;
+          case 'is-bulk':
+            if ($value) {
+              if (PhabricatorEnv::getEnvConfig('metamta.precedence-bulk')) {
+                $mailer->addHeader('Precedence', 'bulk');
+              }
+            }
+            break;
           case 'thread-id':
             if ($is_first && $mailer->supportsMessageIDHeader()) {
               $mailer->addHeader('Message-ID',  $value);
diff --git a/src/applications/repository/worker/herald/PhabricatorRepositoryCommitHeraldWorker.php b/src/applications/repository/worker/herald/PhabricatorRepositoryCommitHeraldWorker.php
index ece3ca535f..3ba9992f49 100644
--- a/src/applications/repository/worker/herald/PhabricatorRepositoryCommitHeraldWorker.php
+++ b/src/applications/repository/worker/herald/PhabricatorRepositoryCommitHeraldWorker.php
@@ -127,6 +127,7 @@ EOBODY;
     $mailer->addTos($email_phids);
     $mailer->setSubject($subject);
     $mailer->setBody($body);
+    $mailer->setIsBulk(true);
 
     $mailer->addHeader('X-Herald-Rules', $xscript->getXHeraldRulesHeader());
     if ($author_phid) {