diff --git a/resources/sql/patches/threadtopic.sql b/resources/sql/patches/threadtopic.sql
new file mode 100644
index 0000000000..cce2ff80fb
--- /dev/null
+++ b/resources/sql/patches/threadtopic.sql
@@ -0,0 +1,14 @@
+ALTER TABLE {$NAMESPACE}_differential.differential_revision
+  ADD originalTitle varchar(255) NOT NULL AFTER title;
+UPDATE {$NAMESPACE}_differential.differential_revision SET
+  originalTitle = title;
+
+ALTER TABLE {$NAMESPACE}_owners.owners_package
+  ADD originalName varchar(255) NOT NULL AFTER name;
+UPDATE {$NAMESPACE}_owners.owners_package SET
+  originalName = name;
+
+ALTER TABLE {$NAMESPACE}_maniphest.maniphest_task
+  ADD originalTitle text NOT NULL AFTER title;
+UPDATE {$NAMESPACE}_maniphest.maniphest_task SET
+  originalTitle = title;
diff --git a/src/applications/audit/editor/PhabricatorAuditCommentEditor.php b/src/applications/audit/editor/PhabricatorAuditCommentEditor.php
index 4b06aa03be..53f76bec3f 100644
--- a/src/applications/audit/editor/PhabricatorAuditCommentEditor.php
+++ b/src/applications/audit/editor/PhabricatorAuditCommentEditor.php
@@ -395,7 +395,9 @@ final class PhabricatorAuditCommentEditor {
 
     $prefix = PhabricatorEnv::getEnvConfig('metamta.diffusion.subject-prefix');
 
-    $threading = self::getMailThreading($commit->getPHID());
+    $repository = id(new PhabricatorRepository())
+      ->load($commit->getRepositoryID());
+    $threading = self::getMailThreading($repository, $commit);
     list($thread_id, $thread_topic) = $threading;
 
     $body       = $this->renderMailBody(
@@ -452,10 +454,13 @@ final class PhabricatorAuditCommentEditor {
     }
   }
 
-  public static function getMailThreading($phid) {
+  public static function getMailThreading(
+    PhabricatorRepository $repository,
+    PhabricatorRepositoryCommit $commit) {
+
     return array(
-      'diffusion-audit-'.$phid,
-      'Diffusion Audit '.$phid,
+      'diffusion-audit-'.$commit->getPHID(),
+      'Commit r'.$repository->getCallsign().$commit->getCommitIdentifier(),
     );
   }
 
diff --git a/src/applications/differential/mail/DifferentialMail.php b/src/applications/differential/mail/DifferentialMail.php
index 7014e2743b..2d1628f023 100644
--- a/src/applications/differential/mail/DifferentialMail.php
+++ b/src/applications/differential/mail/DifferentialMail.php
@@ -328,8 +328,9 @@ EOTEXT;
   }
 
   protected function getThreadTopic() {
-    $phid = $this->getRevision()->getPHID();
-    return "Differential Revision {$phid}";
+    $id = $this->getRevision()->getID();
+    $title = $this->getRevision()->getOriginalTitle();
+    return "D{$id}: {$title}";
   }
 
   public function setComment($comment) {
diff --git a/src/applications/differential/storage/DifferentialRevision.php b/src/applications/differential/storage/DifferentialRevision.php
index 218470b656..44a19ae684 100644
--- a/src/applications/differential/storage/DifferentialRevision.php
+++ b/src/applications/differential/storage/DifferentialRevision.php
@@ -19,6 +19,7 @@
 final class DifferentialRevision extends DifferentialDAO {
 
   protected $title;
+  protected $originalTitle;
   protected $status;
 
   protected $summary;
@@ -60,6 +61,14 @@ final class DifferentialRevision extends DifferentialDAO {
     ) + parent::getConfiguration();
   }
 
+  public function setTitle($title) {
+    $this->title = $title;
+    if (!$this->getID()) {
+      $this->originalTitle = $title;
+    }
+    return $this;
+  }
+
   public function loadCommitPHIDs() {
     if (!$this->getID()) {
       return ($this->commits = array());
diff --git a/src/applications/maniphest/editor/ManiphestTransactionEditor.php b/src/applications/maniphest/editor/ManiphestTransactionEditor.php
index d9307b3aa2..ec6f4518e7 100644
--- a/src/applications/maniphest/editor/ManiphestTransactionEditor.php
+++ b/src/applications/maniphest/editor/ManiphestTransactionEditor.php
@@ -278,7 +278,7 @@ final class ManiphestTransactionEditor {
       ->setVarySubjectPrefix("[{$action}]")
       ->setFrom($transaction->getAuthorPHID())
       ->setParentMessageID($this->parentMessageID)
-      ->addHeader('Thread-Topic', 'Maniphest Task '.$task->getPHID())
+      ->addHeader('Thread-Topic', "T{$task_id}: ".$task->getOriginalTitle())
       ->setThreadID($thread_id, $is_create)
       ->setRelatedPHID($task->getPHID())
       ->setIsBulk(true)
diff --git a/src/applications/maniphest/storage/ManiphestTask.php b/src/applications/maniphest/storage/ManiphestTask.php
index d95084896d..cf0d88d77e 100644
--- a/src/applications/maniphest/storage/ManiphestTask.php
+++ b/src/applications/maniphest/storage/ManiphestTask.php
@@ -31,6 +31,7 @@ final class ManiphestTask extends ManiphestDAO {
   protected $subpriority;
 
   protected $title;
+  protected $originalTitle;
   protected $description;
   protected $originalEmailSource;
   protected $mailKey;
@@ -107,6 +108,14 @@ final class ManiphestTask extends ManiphestDAO {
     return $this;
   }
 
+  public function setTitle($title) {
+    $this->title = $title;
+    if (!$this->getID()) {
+      $this->originalTitle = $title;
+    }
+    return $this;
+  }
+
   public function attachAuxiliaryAttributes(array $attrs) {
     if ($this->auxiliaryDirty) {
       throw new Exception(
diff --git a/src/applications/owners/mail/PackageMail.php b/src/applications/owners/mail/PackageMail.php
index 6be89d2df0..700f83843e 100644
--- a/src/applications/owners/mail/PackageMail.php
+++ b/src/applications/owners/mail/PackageMail.php
@@ -24,7 +24,7 @@ abstract class PackageMail {
   protected $paths;
   protected $mailTo;
 
-  public function __construct($package) {
+  public function __construct(PhabricatorOwnersPackage $package) {
     $this->package = $package;
   }
 
@@ -206,7 +206,7 @@ abstract class PackageMail {
   private function getMailThreading() {
     return array(
       'package-'.$this->getPackage()->getPHID(),
-      'package '.$this->getPackage()->getPHID(),
+      'Package '.$this->getPackage()->getOriginalName(),
     );
   }
 
diff --git a/src/applications/owners/storage/PhabricatorOwnersPackage.php b/src/applications/owners/storage/PhabricatorOwnersPackage.php
index 39f45c14c3..82e2deae3a 100644
--- a/src/applications/owners/storage/PhabricatorOwnersPackage.php
+++ b/src/applications/owners/storage/PhabricatorOwnersPackage.php
@@ -20,6 +20,7 @@ final class PhabricatorOwnersPackage extends PhabricatorOwnersDAO {
 
   protected $phid;
   protected $name;
+  protected $originalName;
   protected $auditingEnabled;
   protected $description;
   protected $primaryOwnerPHID;
@@ -79,6 +80,14 @@ final class PhabricatorOwnersPackage extends PhabricatorOwnersDAO {
     return $this->oldAuditingEnabled;
   }
 
+  public function setName($name) {
+    $this->name = $name;
+    if (!$this->getID()) {
+      $this->originalName = $name;
+    }
+    return $this;
+  }
+
   public function loadOwners() {
     if (!$this->getID()) {
       return array();
diff --git a/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php b/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php
index bcc0b658b7..d6f58b5a63 100644
--- a/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php
+++ b/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php
@@ -153,7 +153,8 @@ EOBODY;
     $prefix = PhabricatorEnv::getEnvConfig('metamta.diffusion.subject-prefix');
 
     $threading = PhabricatorAuditCommentEditor::getMailThreading(
-      $commit->getPHID());
+      $repository,
+      $commit);
     list($thread_id, $thread_topic) = $threading;
 
     $template = new PhabricatorMetaMTAMail();
diff --git a/src/infrastructure/setup/sql/PhabricatorBuiltinPatchList.php b/src/infrastructure/setup/sql/PhabricatorBuiltinPatchList.php
index ac48990cf2..5c3c664595 100644
--- a/src/infrastructure/setup/sql/PhabricatorBuiltinPatchList.php
+++ b/src/infrastructure/setup/sql/PhabricatorBuiltinPatchList.php
@@ -887,6 +887,10 @@ final class PhabricatorBuiltinPatchList extends PhabricatorSQLPatchList {
         'type'    => 'sql',
         'name'    => $this->getPatchPath('ldapinfo.sql'),
       ),
+      'threadtopic.sql' => array(
+        'type'    => 'sql',
+        'name'    => $this->getPatchPath('threadtopic.sql'),
+      ),
     );
   }