diff --git a/src/applications/audit/mail/PhabricatorAuditMailReceiver.php b/src/applications/audit/mail/PhabricatorAuditMailReceiver.php
index 9dc70e9d8a..9b55151747 100644
--- a/src/applications/audit/mail/PhabricatorAuditMailReceiver.php
+++ b/src/applications/audit/mail/PhabricatorAuditMailReceiver.php
@@ -12,7 +12,7 @@ final class PhabricatorAuditMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)preg_replace('/^COMMIT/', '', $pattern);
+    $id = (int)preg_replace('/^COMMIT/i', '', $pattern);
 
     return id(new DiffusionCommitQuery())
       ->setViewer($viewer)
diff --git a/src/applications/calendar/mail/PhabricatorCalendarEventMailReceiver.php b/src/applications/calendar/mail/PhabricatorCalendarEventMailReceiver.php
index 8536907486..01a0367234 100644
--- a/src/applications/calendar/mail/PhabricatorCalendarEventMailReceiver.php
+++ b/src/applications/calendar/mail/PhabricatorCalendarEventMailReceiver.php
@@ -13,7 +13,7 @@ final class PhabricatorCalendarEventMailReceiver
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'E');
+    $id = (int)substr($pattern, 1);
 
     return id(new PhabricatorCalendarEventQuery())
       ->setViewer($viewer)
diff --git a/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php b/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
index e597c52897..12b9463166 100644
--- a/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
+++ b/src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
@@ -394,6 +394,10 @@ final class PhabricatorExtraConfigSetupCheck extends PhabricatorSetupCheck {
 
       'metamta.insecure-auth-with-reply-to' => pht(
         'Authenticating users based on "Reply-To" is no longer supported.'),
+
+      'phabricator.allow-email-users' => pht(
+        'Public email is now accepted if the associated address has a '.
+        'default author, and rejected otherwise.'),
     );
 
     return $ancient_config;
diff --git a/src/applications/config/option/PhabricatorCoreConfigOptions.php b/src/applications/config/option/PhabricatorCoreConfigOptions.php
index 08266217ea..48f6f24491 100644
--- a/src/applications/config/option/PhabricatorCoreConfigOptions.php
+++ b/src/applications/config/option/PhabricatorCoreConfigOptions.php
@@ -234,14 +234,6 @@ EOREMARKUP
       $this->newOption('phabricator.cache-namespace', 'string', 'phabricator')
         ->setLocked(true)
         ->setDescription(pht('Cache namespace.')),
-      $this->newOption('phabricator.allow-email-users', 'bool', false)
-        ->setBoolOptions(
-          array(
-            pht('Allow'),
-            pht('Disallow'),
-          ))
-        ->setDescription(
-           pht('Allow non-members to interact with tasks over email.')),
       $this->newOption('phabricator.silent', 'bool', false)
         ->setLocked(true)
         ->setBoolOptions(
diff --git a/src/applications/conpherence/mail/ConpherenceThreadMailReceiver.php b/src/applications/conpherence/mail/ConpherenceThreadMailReceiver.php
index e926d3cfc5..aeb4e28997 100644
--- a/src/applications/conpherence/mail/ConpherenceThreadMailReceiver.php
+++ b/src/applications/conpherence/mail/ConpherenceThreadMailReceiver.php
@@ -13,7 +13,7 @@ final class ConpherenceThreadMailReceiver
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'Z');
+    $id = (int)substr($pattern, 1);
 
     return id(new ConpherenceThreadQuery())
       ->setViewer($viewer)
diff --git a/src/applications/countdown/mail/PhabricatorCountdownMailReceiver.php b/src/applications/countdown/mail/PhabricatorCountdownMailReceiver.php
index d0218de59b..9b448ef10f 100644
--- a/src/applications/countdown/mail/PhabricatorCountdownMailReceiver.php
+++ b/src/applications/countdown/mail/PhabricatorCountdownMailReceiver.php
@@ -13,7 +13,7 @@ final class PhabricatorCountdownMailReceiver
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)substr($pattern, 4);
+    $id = (int)substr($pattern, 1);
 
     return id(new PhabricatorCountdownQuery())
       ->setViewer($viewer)
diff --git a/src/applications/differential/mail/DifferentialCreateMailReceiver.php b/src/applications/differential/mail/DifferentialCreateMailReceiver.php
index cfd7470099..0d4fd1a2be 100644
--- a/src/applications/differential/mail/DifferentialCreateMailReceiver.php
+++ b/src/applications/differential/mail/DifferentialCreateMailReceiver.php
@@ -9,14 +9,16 @@ final class DifferentialCreateMailReceiver
 
   protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
+    PhutilEmailAddress $target) {
+
+    $author = $this->getAuthor();
 
     $attachments = $mail->getAttachments();
     $files = array();
     $errors = array();
     if ($attachments) {
       $files = id(new PhabricatorFileQuery())
-        ->setViewer($sender)
+        ->setViewer($author)
         ->withPHIDs($attachments)
         ->execute();
       foreach ($files as $index => $file) {
@@ -37,7 +39,7 @@ final class DifferentialCreateMailReceiver
         array(
           'diff' => $file->loadFileData(),
         ));
-      $call->setUser($sender);
+      $call->setUser($author);
       try {
         $result = $call->execute();
         $diffs[$file->getName()] = $result['uri'];
@@ -56,7 +58,7 @@ final class DifferentialCreateMailReceiver
         array(
           'diff' => $body,
         ));
-      $call->setUser($sender);
+      $call->setUser($author);
       try {
         $result = $call->execute();
         $diffs[pht('Mail Body')] = $result['uri'];
@@ -108,10 +110,10 @@ final class DifferentialCreateMailReceiver
     }
 
     id(new PhabricatorMetaMTAMail())
-      ->addTos(array($sender->getPHID()))
+      ->addTos(array($author->getPHID()))
       ->setSubject($subject)
       ->setSubjectPrefix($subject_prefix)
-      ->setFrom($sender->getPHID())
+      ->setFrom($author->getPHID())
       ->setBody($body->render())
       ->saveAndSend();
   }
diff --git a/src/applications/differential/mail/DifferentialRevisionMailReceiver.php b/src/applications/differential/mail/DifferentialRevisionMailReceiver.php
index 929ee72647..0fe8583a1d 100644
--- a/src/applications/differential/mail/DifferentialRevisionMailReceiver.php
+++ b/src/applications/differential/mail/DifferentialRevisionMailReceiver.php
@@ -13,7 +13,7 @@ final class DifferentialRevisionMailReceiver
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'D');
+    $id = (int)substr($pattern, 1);
 
     return id(new DifferentialRevisionQuery())
       ->setViewer($viewer)
diff --git a/src/applications/files/mail/FileCreateMailReceiver.php b/src/applications/files/mail/FileCreateMailReceiver.php
index 2cf946aea8..fe314f1f0a 100644
--- a/src/applications/files/mail/FileCreateMailReceiver.php
+++ b/src/applications/files/mail/FileCreateMailReceiver.php
@@ -9,7 +9,8 @@ final class FileCreateMailReceiver
 
   protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
+    PhutilEmailAddress $target) {
+    $author = $this->getAuthor();
 
     $attachment_phids = $mail->getAttachments();
     if (empty($attachment_phids)) {
@@ -21,6 +22,11 @@ final class FileCreateMailReceiver
     $first_phid = head($attachment_phids);
     $mail->setRelatedPHID($first_phid);
 
+    $sender = $this->getSender();
+    if (!$sender) {
+      return;
+    }
+
     $attachment_count = count($attachment_phids);
     if ($attachment_count > 1) {
       $subject = pht('You successfully uploaded %d files.', $attachment_count);
diff --git a/src/applications/files/mail/FileMailReceiver.php b/src/applications/files/mail/FileMailReceiver.php
index cdad22c5ce..f4074d9ba0 100644
--- a/src/applications/files/mail/FileMailReceiver.php
+++ b/src/applications/files/mail/FileMailReceiver.php
@@ -12,7 +12,7 @@ final class FileMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'F');
+    $id = (int)substr($pattern, 1);
 
     return id(new PhabricatorFileQuery())
       ->setViewer($viewer)
diff --git a/src/applications/legalpad/mail/LegalpadMailReceiver.php b/src/applications/legalpad/mail/LegalpadMailReceiver.php
index 5fe0dfd4e8..679812e4ad 100644
--- a/src/applications/legalpad/mail/LegalpadMailReceiver.php
+++ b/src/applications/legalpad/mail/LegalpadMailReceiver.php
@@ -12,7 +12,7 @@ final class LegalpadMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'L');
+    $id = (int)substr($pattern, 1);
 
     return id(new LegalpadDocumentQuery())
       ->setViewer($viewer)
diff --git a/src/applications/maniphest/mail/ManiphestCreateMailReceiver.php b/src/applications/maniphest/mail/ManiphestCreateMailReceiver.php
index 64bdaa2ed5..22c09fdf60 100644
--- a/src/applications/maniphest/mail/ManiphestCreateMailReceiver.php
+++ b/src/applications/maniphest/mail/ManiphestCreateMailReceiver.php
@@ -9,15 +9,20 @@ final class ManiphestCreateMailReceiver
 
   protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
+    PhutilEmailAddress $target) {
 
-    $task = ManiphestTask::initializeNewTask($sender);
-    $task->setOriginalEmailSource($mail->getHeader('From'));
+    $author = $this->getAuthor();
+    $task = ManiphestTask::initializeNewTask($author);
+
+    $from_address = $mail->newFromAddress();
+    if ($from_address) {
+      $task->setOriginalEmailSource((string)$from_address);
+    }
 
     $handler = new ManiphestReplyHandler();
     $handler->setMailReceiver($task);
 
-    $handler->setActor($sender);
+    $handler->setActor($author);
     $handler->setExcludeMailRecipientPHIDs(
       $mail->loadAllRecipientPHIDs());
     if ($this->getApplicationEmail()) {
diff --git a/src/applications/maniphest/mail/ManiphestTaskMailReceiver.php b/src/applications/maniphest/mail/ManiphestTaskMailReceiver.php
index 220a888e8e..54ac72fd57 100644
--- a/src/applications/maniphest/mail/ManiphestTaskMailReceiver.php
+++ b/src/applications/maniphest/mail/ManiphestTaskMailReceiver.php
@@ -12,7 +12,7 @@ final class ManiphestTaskMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'T');
+    $id = (int)substr($pattern, 1);
 
     return id(new ManiphestTaskQuery())
       ->setViewer($viewer)
diff --git a/src/applications/metamta/applicationpanel/PhabricatorMetaMTAApplicationEmailPanel.php b/src/applications/metamta/applicationpanel/PhabricatorMetaMTAApplicationEmailPanel.php
index afde9fee23..c13835e6f4 100644
--- a/src/applications/metamta/applicationpanel/PhabricatorMetaMTAApplicationEmailPanel.php
+++ b/src/applications/metamta/applicationpanel/PhabricatorMetaMTAApplicationEmailPanel.php
@@ -261,8 +261,12 @@ final class PhabricatorMetaMTAApplicationEmailPanel
           ->setName($config_default)
           ->setLimit(1)
           ->setValue($v_default)
-          ->setCaption(pht(
-            'Used if the "From:" address does not map to a known account.')));
+          ->setCaption(
+            pht(
+              'Used if the "From:" address does not map to a user account. '.
+              'Setting a default author will allow anyone on the public '.
+              'internet to create objects in Phabricator by sending email to '.
+              'this address.')));
 
     if ($is_new) {
       $title = pht('New Address');
@@ -369,9 +373,17 @@ final class PhabricatorMetaMTAApplicationEmailPanel
         $email_space = null;
       }
 
+      $default_author_phid = $email->getDefaultAuthorPHID();
+      if (!$default_author_phid) {
+        $default_author = phutil_tag('em', array(), pht('None'));
+      } else {
+        $default_author = $viewer->renderHandle($default_author_phid);
+      }
+
       $rows[] = array(
         $email_space,
         $email->getAddress(),
+        $default_author,
         $button_edit,
         $button_remove,
       );
@@ -383,11 +395,13 @@ final class PhabricatorMetaMTAApplicationEmailPanel
       array(
         pht('Space'),
         pht('Email'),
+        pht('Default'),
         pht('Edit'),
         pht('Delete'),
       ));
     $table->setColumnClasses(
       array(
+        '',
         '',
         'wide',
         'action',
@@ -398,6 +412,7 @@ final class PhabricatorMetaMTAApplicationEmailPanel
       array(
         PhabricatorSpacesNamespaceQuery::getViewerSpacesExist($viewer),
         true,
+        true,
         $is_edit,
         $is_edit,
       ));
diff --git a/src/applications/metamta/constants/MetaMTAReceivedMailStatus.php b/src/applications/metamta/constants/MetaMTAReceivedMailStatus.php
index 965bdbdbfe..2ec44b847a 100644
--- a/src/applications/metamta/constants/MetaMTAReceivedMailStatus.php
+++ b/src/applications/metamta/constants/MetaMTAReceivedMailStatus.php
@@ -6,7 +6,6 @@ final class MetaMTAReceivedMailStatus
   const STATUS_DUPLICATE            = 'err:duplicate';
   const STATUS_FROM_PHABRICATOR     = 'err:self';
   const STATUS_NO_RECEIVERS         = 'err:no-receivers';
-  const STATUS_ABUNDANT_RECEIVERS   = 'err:multiple-receivers';
   const STATUS_UNKNOWN_SENDER       = 'err:unknown-sender';
   const STATUS_DISABLED_SENDER      = 'err:disabled-sender';
   const STATUS_NO_PUBLIC_MAIL       = 'err:no-public-mail';
@@ -23,7 +22,6 @@ final class MetaMTAReceivedMailStatus
       self::STATUS_DUPLICATE => pht('Duplicate Message'),
       self::STATUS_FROM_PHABRICATOR => pht('Phabricator Mail'),
       self::STATUS_NO_RECEIVERS => pht('No Receivers'),
-      self::STATUS_ABUNDANT_RECEIVERS => pht('Multiple Receivers'),
       self::STATUS_UNKNOWN_SENDER => pht('Unknown Sender'),
       self::STATUS_DISABLED_SENDER => pht('Disabled Sender'),
       self::STATUS_NO_PUBLIC_MAIL => pht('No Public Mail'),
diff --git a/src/applications/metamta/management/PhabricatorMailManagementReceiveTestWorkflow.php b/src/applications/metamta/management/PhabricatorMailManagementReceiveTestWorkflow.php
index 46c444571b..5c17b11321 100644
--- a/src/applications/metamta/management/PhabricatorMailManagementReceiveTestWorkflow.php
+++ b/src/applications/metamta/management/PhabricatorMailManagementReceiveTestWorkflow.php
@@ -33,6 +33,7 @@ final class PhabricatorMailManagementReceiveTestWorkflow
   }
 
   public function execute(PhutilArgumentParser $args) {
+    $viewer = $this->getViewer();
     $console = PhutilConsole::getConsole();
 
     $to = $args->getArg('to');
@@ -95,14 +96,23 @@ final class PhabricatorMailManagementReceiveTestWorkflow
     if (preg_match('/.+@.+/', $to)) {
       $header_content['to'] = $to;
     } else {
+
       // We allow the user to use an object name instead of a real address
       // as a convenience. To build the mail, we build a similar message and
       // look for a receiver which will accept it.
+
+      // In the general case, mail may be processed by multiple receivers,
+      // but mail to objects only ever has one receiver today.
+
       $pseudohash = PhabricatorObjectMailReceiver::computeMailHash('x', 'y');
+
+      $raw_target = $to.'+1+'.$pseudohash;
+      $target = new PhutilEmailAddress($raw_target.'@local.cli');
+
       $pseudomail = id(new PhabricatorMetaMTAReceivedMail())
         ->setHeaders(
           array(
-            'to' => $to.'+1+'.$pseudohash,
+            'to' => $raw_target,
           ));
 
       $receivers = id(new PhutilClassMapQuery())
@@ -112,7 +122,11 @@ final class PhabricatorMailManagementReceiveTestWorkflow
 
       $receiver = null;
       foreach ($receivers as $possible_receiver) {
-        if (!$possible_receiver->canAcceptMail($pseudomail)) {
+        $possible_receiver = id(clone $possible_receiver)
+          ->setViewer($viewer)
+          ->setSender($user);
+
+        if (!$possible_receiver->canAcceptMail($pseudomail, $target)) {
           continue;
         }
         $receiver = $possible_receiver;
diff --git a/src/applications/metamta/query/PhabricatorMetaMTAActorQuery.php b/src/applications/metamta/query/PhabricatorMetaMTAActorQuery.php
index 18b8063ee1..269b9824a5 100644
--- a/src/applications/metamta/query/PhabricatorMetaMTAActorQuery.php
+++ b/src/applications/metamta/query/PhabricatorMetaMTAActorQuery.php
@@ -121,12 +121,12 @@ final class PhabricatorMetaMTAActorQuery extends PhabricatorQuery {
 
       $actor->setEmailAddress($xuser->getAccountID());
 
-      // NOTE: This effectively drops all outbound mail to unrecognized
-      // addresses unless "phabricator.allow-email-users" is set. See T12237
-      // for context.
-      $allow_key = 'phabricator.allow-email-users';
-      $allow_value = PhabricatorEnv::getEnvConfig($allow_key);
-      $actor->setIsVerified((bool)$allow_value);
+      // Circa T7477, it appears that we never intentionally send email to
+      // external users (even when they email "bugs@" to create a task).
+      // Mark these users as unverified so mail to them is always dropped.
+      // See also T12237. In the future, we might change this behavior.
+
+      $actor->setIsVerified(false);
     }
   }
 
diff --git a/src/applications/metamta/receiver/PhabricatorApplicationMailReceiver.php b/src/applications/metamta/receiver/PhabricatorApplicationMailReceiver.php
index 11646351f2..546f622e10 100644
--- a/src/applications/metamta/receiver/PhabricatorApplicationMailReceiver.php
+++ b/src/applications/metamta/receiver/PhabricatorApplicationMailReceiver.php
@@ -3,32 +3,105 @@
 abstract class PhabricatorApplicationMailReceiver
   extends PhabricatorMailReceiver {
 
+  private $applicationEmail;
+  private $emailList;
+  private $author;
+
   abstract protected function newApplication();
 
+  final protected function setApplicationEmail(
+    PhabricatorMetaMTAApplicationEmail $email) {
+    $this->applicationEmail = $email;
+    return $this;
+  }
+
+  final protected function getApplicationEmail() {
+    return $this->applicationEmail;
+  }
+
+  final protected function setAuthor(PhabricatorUser $author) {
+    $this->author = $author;
+    return $this;
+  }
+
+  final protected function getAuthor() {
+    return $this->author;
+  }
+
   final public function isEnabled() {
     return $this->newApplication()->isInstalled();
   }
 
-  final public function canAcceptMail(PhabricatorMetaMTAReceivedMail $mail) {
-    $application = $this->newApplication();
+  final public function canAcceptMail(
+    PhabricatorMetaMTAReceivedMail $mail,
+    PhutilEmailAddress $target) {
+
     $viewer = $this->getViewer();
+    $sender = $this->getSender();
 
-    $application_emails = id(new PhabricatorMetaMTAApplicationEmailQuery())
-      ->setViewer($viewer)
-      ->withApplicationPHIDs(array($application->getPHID()))
-      ->execute();
+    foreach ($this->loadApplicationEmailList() as $application_email) {
+      $create_address = $application_email->newAddress();
 
-    foreach ($mail->newTargetAddresses() as $address) {
-      foreach ($application_emails as $application_email) {
-        $create_address = $application_email->newAddress();
-        if (PhabricatorMailUtil::matchAddresses($create_address, $address)) {
-          $this->setApplicationEmail($application_email);
-          return true;
+      if (!PhabricatorMailUtil::matchAddresses($create_address, $target)) {
+        continue;
+      }
+
+      if ($sender) {
+        $author = $sender;
+      } else {
+        $author_phid = $application_email->getDefaultAuthorPHID();
+
+        // If this mail isn't from a recognized sender and the target address
+        // does not have a default author, we can't accept it, and it's an
+        // error because you tried to send it here.
+
+        // You either need to be sending from a real address or be sending to
+        // an address which accepts mail from the public internet.
+
+        if (!$author_phid) {
+          throw new PhabricatorMetaMTAReceivedMailProcessingException(
+            MetaMTAReceivedMailStatus::STATUS_UNKNOWN_SENDER,
+            pht(
+              'You are sending from an unrecognized email address to '.
+              'an address which does not support public email ("%s").',
+              (string)$target));
+        }
+
+        $author = id(new PhabricatorPeopleQuery())
+          ->setViewer($viewer)
+          ->withPHIDs(array($author_phid))
+          ->executeOne();
+        if (!$author) {
+          throw new Exception(
+            pht(
+              'Application email ("%s") has an invalid default author ("%s").',
+              (string)$create_address,
+              $author_phid));
         }
       }
+
+      $this
+        ->setApplicationEmail($application_email)
+        ->setAuthor($author);
+
+      return true;
     }
 
     return false;
   }
 
+  private function loadApplicationEmailList() {
+    if ($this->emailList === null) {
+      $viewer = $this->getViewer();
+      $application = $this->newApplication();
+
+      $this->emailList = id(new PhabricatorMetaMTAApplicationEmailQuery())
+        ->setViewer($viewer)
+        ->withApplicationPHIDs(array($application->getPHID()))
+        ->execute();
+    }
+
+    return $this->emailList;
+  }
+
 }
diff --git a/src/applications/metamta/receiver/PhabricatorMailReceiver.php b/src/applications/metamta/receiver/PhabricatorMailReceiver.php
index 9f2e979815..738f8d9e26 100644
--- a/src/applications/metamta/receiver/PhabricatorMailReceiver.php
+++ b/src/applications/metamta/receiver/PhabricatorMailReceiver.php
@@ -2,167 +2,40 @@
 
 abstract class PhabricatorMailReceiver extends Phobject {
 
-  private $applicationEmail;
+  private $viewer;
+  private $sender;
 
-  public function setApplicationEmail(
-    PhabricatorMetaMTAApplicationEmail $email) {
-    $this->applicationEmail = $email;
+  final public function setViewer(PhabricatorUser $viewer) {
+    $this->viewer = $viewer;
     return $this;
   }
 
-  public function getApplicationEmail() {
-    return $this->applicationEmail;
+  final public function getViewer() {
+    return $this->viewer;
+  }
+
+  final public function setSender(PhabricatorUser $sender) {
+    $this->sender = $sender;
+    return $this;
+  }
+
+  final public function getSender() {
+    return $this->sender;
   }
 
   abstract public function isEnabled();
-  abstract public function canAcceptMail(PhabricatorMetaMTAReceivedMail $mail);
+  abstract public function canAcceptMail(
+    PhabricatorMetaMTAReceivedMail $mail,
+    PhutilEmailAddress $target);
 
   abstract protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender);
+    PhutilEmailAddress $target);
 
   final public function receiveMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
-    $this->processReceivedMail($mail, $sender);
-  }
-
-  public function getViewer() {
-    return PhabricatorUser::getOmnipotentUser();
-  }
-
-  public function validateSender(
-    PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
-
-    $failure_reason = null;
-    if ($sender->getIsDisabled()) {
-      $failure_reason = pht(
-        'Your account (%s) is disabled, so you can not interact with '.
-        'Phabricator over email.',
-        $sender->getUsername());
-    } else if ($sender->getIsStandardUser()) {
-      if (!$sender->getIsApproved()) {
-        $failure_reason = pht(
-          'Your account (%s) has not been approved yet. You can not interact '.
-          'with Phabricator over email until your account is approved.',
-          $sender->getUsername());
-      } else if (PhabricatorUserEmail::isEmailVerificationRequired() &&
-               !$sender->getIsEmailVerified()) {
-        $failure_reason = pht(
-          'You have not verified the email address for your account (%s). '.
-          'You must verify your email address before you can interact '.
-          'with Phabricator over email.',
-          $sender->getUsername());
-      }
-    }
-
-    if ($failure_reason) {
-      throw new PhabricatorMetaMTAReceivedMailProcessingException(
-        MetaMTAReceivedMailStatus::STATUS_DISABLED_SENDER,
-        $failure_reason);
-    }
-  }
-
-  /**
-   * Identifies the sender's user account for a piece of received mail. Note
-   * that this method does not validate that the sender is who they say they
-   * are, just that they've presented some credential which corresponds to a
-   * recognizable user.
-   */
-  public function loadSender(PhabricatorMetaMTAReceivedMail $mail) {
-    $raw_from = $mail->getHeader('From');
-    $from = self::getRawAddress($raw_from);
-
-    $reasons = array();
-
-    // Try to find a user with this email address.
-    $user = PhabricatorUser::loadOneWithEmailAddress($from);
-    if ($user) {
-      return $user;
-    } else {
-      $reasons[] = pht(
-        'This email was sent from "%s", but that address is not recognized by '.
-        'Phabricator and does not correspond to any known user account.',
-        $raw_from);
-    }
-
-    // If we don't know who this user is, load or create an external user
-    // account for them if we're configured for it.
-    $email_key = 'phabricator.allow-email-users';
-    $allow_email_users = PhabricatorEnv::getEnvConfig($email_key);
-    if ($allow_email_users) {
-      $from_obj = new PhutilEmailAddress($from);
-      $xuser = id(new PhabricatorExternalAccountQuery())
-        ->setViewer($this->getViewer())
-        ->withAccountTypes(array('email'))
-        ->withAccountDomains(array($from_obj->getDomainName(), 'self'))
-        ->withAccountIDs(array($from_obj->getAddress()))
-        ->requireCapabilities(
-          array(
-            PhabricatorPolicyCapability::CAN_VIEW,
-            PhabricatorPolicyCapability::CAN_EDIT,
-          ))
-        ->loadOneOrCreate();
-      return $xuser->getPhabricatorUser();
-    } else {
-      // NOTE: Currently, we'll always drop this mail (since it's headed to
-      // an unverified recipient). See T12237. These details are still useful
-      // because they'll appear in the mail logs and Mail web UI.
-
-      $reasons[] = pht(
-        'Phabricator is also not configured to allow unknown external users '.
-        'to send mail to the system using just an email address.');
-      $reasons[] = pht(
-        'To interact with Phabricator, add this address ("%s") to your '.
-        'account.',
-        $raw_from);
-    }
-
-    if ($this->getApplicationEmail()) {
-      $application_email = $this->getApplicationEmail();
-      $default_user_phid = $application_email->getConfigValue(
-        PhabricatorMetaMTAApplicationEmail::CONFIG_DEFAULT_AUTHOR);
-
-      if ($default_user_phid) {
-        $user = id(new PhabricatorUser())->loadOneWhere(
-          'phid = %s',
-          $default_user_phid);
-        if ($user) {
-          return $user;
-        }
-
-        $reasons[] = pht(
-          'Phabricator is misconfigured: the application email '.
-          '"%s" is set to user "%s", but that user does not exist.',
-          $application_email->getAddress(),
-          $default_user_phid);
-      }
-    }
-
-    $reasons = implode("\n\n", $reasons);
-
-    throw new PhabricatorMetaMTAReceivedMailProcessingException(
-      MetaMTAReceivedMailStatus::STATUS_UNKNOWN_SENDER,
-      $reasons);
-  }
-
-  /**
-   * Reduce an email address to its canonical form. For example, an address
-   * like:
-   *
-   *  "Abraham Lincoln" < ALincoln@example.com >
-   *
-   * ...will be reduced to:
-   *
-   *  alincoln@example.com
-   *
-   * @param   string  Email address in noncanonical form.
-   * @return  string  Canonical email address.
-   */
-  public static function getRawAddress($address) {
-    $address = id(new PhutilEmailAddress($address))->getAddress();
-    return trim(phutil_utf8_strtolower($address));
+    PhutilEmailAddress $target) {
+    $this->processReceivedMail($mail, $target);
   }
 
 }
diff --git a/src/applications/metamta/receiver/PhabricatorObjectMailReceiver.php b/src/applications/metamta/receiver/PhabricatorObjectMailReceiver.php
index 9f92d33f21..16950c1577 100644
--- a/src/applications/metamta/receiver/PhabricatorObjectMailReceiver.php
+++ b/src/applications/metamta/receiver/PhabricatorObjectMailReceiver.php
@@ -29,52 +29,23 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
 
   final protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
+    PhutilEmailAddress $target) {
 
-    $object = $this->loadObjectFromMail($mail, $sender);
-    $mail->setRelatedPHID($object->getPHID());
-
-    $this->processReceivedObjectMail($mail, $object, $sender);
-
-    return $this;
-  }
-
-  protected function processReceivedObjectMail(
-    PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorLiskDAO $object,
-    PhabricatorUser $sender) {
-
-    $handler = $this->getTransactionReplyHandler();
-    if ($handler) {
-      return $handler
-        ->setMailReceiver($object)
-        ->setActor($sender)
-        ->setExcludeMailRecipientPHIDs($mail->loadAllRecipientPHIDs())
-        ->processEmail($mail);
+    $parts = $this->matchObjectAddress($target);
+    if (!$parts) {
+      // We should only make it here if we matched already in "canAcceptMail()",
+      // so this is a surprise.
+      throw new Exception(
+        pht(
+          'Failed to parse object address ("%s") during processing.',
+          (string)$target));
     }
 
-    throw new PhutilMethodNotImplementedException();
-  }
-
-  protected function getTransactionReplyHandler() {
-    return null;
-  }
-
-  public function loadMailReceiverObject($pattern, PhabricatorUser $viewer) {
-    return $this->loadObject($pattern, $viewer);
-  }
-
-  public function validateSender(
-    PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
-
-    parent::validateSender($mail, $sender);
-
-    $parts = $this->matchObjectAddressInMail($mail);
     $pattern = $parts['pattern'];
+    $sender = $this->getSender();
 
     try {
-      $object = $this->loadObjectFromMail($mail, $sender);
+      $object = $this->loadObject($pattern, $sender);
     } catch (PhabricatorPolicyException $policy_exception) {
       throw new PhabricatorMetaMTAReceivedMailProcessingException(
         MetaMTAReceivedMailStatus::STATUS_POLICY_PROBLEM,
@@ -95,7 +66,6 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
     }
 
     $sender_identifier = $parts['sender'];
-
     if ($sender_identifier === 'public') {
       if (!PhabricatorEnv::getEnvConfig('metamta.public-replies')) {
         throw new PhabricatorMetaMTAReceivedMailProcessingException(
@@ -136,30 +106,52 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
           'is correct.',
           $pattern));
     }
+
+    $mail->setRelatedPHID($object->getPHID());
+    $this->processReceivedObjectMail($mail, $object, $sender);
+
+    return $this;
   }
 
+  protected function processReceivedObjectMail(
+    PhabricatorMetaMTAReceivedMail $mail,
+    PhabricatorLiskDAO $object,
+    PhabricatorUser $sender) {
 
-  final public function canAcceptMail(PhabricatorMetaMTAReceivedMail $mail) {
-    if ($this->matchObjectAddressInMail($mail)) {
-      return true;
+    $handler = $this->getTransactionReplyHandler();
+    if ($handler) {
+      return $handler
+        ->setMailReceiver($object)
+        ->setActor($sender)
+        ->setExcludeMailRecipientPHIDs($mail->loadAllRecipientPHIDs())
+        ->processEmail($mail);
     }
 
-    return false;
+    throw new PhutilMethodNotImplementedException();
   }
 
-  private function matchObjectAddressInMail(
-    PhabricatorMetaMTAReceivedMail $mail) {
-
-    foreach ($mail->newTargetAddresses() as $address) {
-      $parts = $this->matchObjectAddress($address);
-      if ($parts) {
-        return $parts;
-      }
-    }
-
+  protected function getTransactionReplyHandler() {
     return null;
   }
 
+  public function loadMailReceiverObject($pattern, PhabricatorUser $viewer) {
+    return $this->loadObject($pattern, $viewer);
+  }
+
+  final public function canAcceptMail(
+    PhabricatorMetaMTAReceivedMail $mail,
+    PhutilEmailAddress $target) {
+
+    // If we don't have a valid sender user account, we can never accept
+    // mail to any object.
+    $sender = $this->getSender();
+    if (!$sender) {
+      return false;
+    }
+
+    return (bool)$this->matchObjectAddress($target);
+  }
+
   private function matchObjectAddress(PhutilEmailAddress $address) {
     $address = PhabricatorMailUtil::normalizeAddress($address);
     $local = $address->getLocalPart();
@@ -188,16 +180,6 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
     return $regexp;
   }
 
-  private function loadObjectFromMail(
-    PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
-    $parts = $this->matchObjectAddressInMail($mail);
-
-    return $this->loadObject(
-      phutil_utf8_strtoupper($parts['pattern']),
-      $sender);
-  }
-
   public static function computeMailHash($mail_key, $phid) {
     $hash = PhabricatorHash::digestWithNamedKey(
       $mail_key.$phid,
diff --git a/src/applications/metamta/storage/PhabricatorMetaMTAApplicationEmail.php b/src/applications/metamta/storage/PhabricatorMetaMTAApplicationEmail.php
index f9698c3928..f5673bed9d 100644
--- a/src/applications/metamta/storage/PhabricatorMetaMTAApplicationEmail.php
+++ b/src/applications/metamta/storage/PhabricatorMetaMTAApplicationEmail.php
@@ -67,6 +67,9 @@ final class PhabricatorMetaMTAApplicationEmail
     return idx($this->configData, $key, $default);
   }
 
+  public function getDefaultAuthorPHID() {
+    return $this->getConfigValue(self::CONFIG_DEFAULT_AUTHOR);
+  }
 
   public function getInUseMessage() {
     $applications = PhabricatorApplication::getAllApplications();
diff --git a/src/applications/metamta/storage/PhabricatorMetaMTAReceivedMail.php b/src/applications/metamta/storage/PhabricatorMetaMTAReceivedMail.php
index 95f6048c01..0605c99b89 100644
--- a/src/applications/metamta/storage/PhabricatorMetaMTAReceivedMail.php
+++ b/src/applications/metamta/storage/PhabricatorMetaMTAReceivedMail.php
@@ -125,6 +125,7 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
   }
 
   public function processReceivedMail() {
+    $viewer = $this->getViewer();
 
     $sender = null;
     try {
@@ -132,26 +133,94 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
       $this->dropMailAlreadyReceived();
       $this->dropEmptyMail();
 
-      $receiver = $this->loadReceiver();
-      $sender = $receiver->loadSender($this);
-      $receiver->validateSender($this, $sender);
+      $sender = $this->loadSender();
+      if ($sender) {
+        $this->setAuthorPHID($sender->getPHID());
 
-      $this->setAuthorPHID($sender->getPHID());
+        // If we've identified the sender, mark them as the author of any
+        // attached files. We do this before we validate them (below), since
+        // they still authored these files even if their account is not allowed
+        // to interact via email.
 
-      // Now that we've identified the sender, mark them as the author of
-      // any attached files.
-      $attachments = $this->getAttachments();
-      if ($attachments) {
-        $files = id(new PhabricatorFileQuery())
-          ->setViewer(PhabricatorUser::getOmnipotentUser())
-          ->withPHIDs($attachments)
-          ->execute();
-        foreach ($files as $file) {
-          $file->setAuthorPHID($sender->getPHID())->save();
+        $attachments = $this->getAttachments();
+        if ($attachments) {
+          $files = id(new PhabricatorFileQuery())
+            ->setViewer($viewer)
+            ->withPHIDs($attachments)
+            ->execute();
+          foreach ($files as $file) {
+            $file->setAuthorPHID($sender->getPHID())->save();
+          }
+        }
+
+        $this->validateSender($sender);
+      }
+
+      $receivers = id(new PhutilClassMapQuery())
+        ->setAncestorClass('PhabricatorMailReceiver')
+        ->setFilterMethod('isEnabled')
+        ->execute();
+
+      $any_accepted = false;
+      $receiver_exception = null;
+
+      $targets = $this->newTargetAddresses();
+      foreach ($receivers as $receiver) {
+        $receiver = id(clone $receiver)
+          ->setViewer($viewer);
+
+        if ($sender) {
+          $receiver->setSender($sender);
+        }
+
+        foreach ($targets as $target) {
+          try {
+            if (!$receiver->canAcceptMail($this, $target)) {
+              continue;
+            }
+
+            $any_accepted = true;
+
+            $receiver->receiveMail($this, $target);
+          } catch (Exception $ex) {
+            // If receivers raise exceptions, we'll keep the first one in hope
+            // that it points at a root cause.
+            if (!$receiver_exception) {
+              $receiver_exception = $ex;
+            }
+          }
         }
       }
 
-      $receiver->receiveMail($this, $sender);
+      if ($receiver_exception) {
+        throw $receiver_exception;
+      }
+
+      if (!$any_accepted) {
+        if (!$sender) {
+          // NOTE: Currently, we'll always drop this mail (since it's headed to
+          // an unverified recipient). See T12237. These details are still
+          // useful because they'll appear in the mail logs and Mail web UI.
+
+          throw new PhabricatorMetaMTAReceivedMailProcessingException(
+            MetaMTAReceivedMailStatus::STATUS_UNKNOWN_SENDER,
+            pht(
+              'This email was sent from an email address ("%s") that is not '.
+              'associated with a Phabricator account. To interact with '.
+              'Phabricator via email, add this address to your account.',
+              (string)$this->newFromAddress()));
+        } else {
+          throw new PhabricatorMetaMTAReceivedMailProcessingException(
+            MetaMTAReceivedMailStatus::STATUS_NO_RECEIVERS,
+            pht(
+              'Phabricator can not process this mail because no application '.
+              'knows how to handle it. Check that the address you sent it to '.
+              'is correct.'.
+              "\n\n".
+              '(No concrete, enabled subclass of PhabricatorMailReceiver can '.
+              'accept this mail.)'));
+        }
+      }
     } catch (PhabricatorMetaMTAReceivedMailProcessingException $ex) {
       switch ($ex->getStatusCode()) {
         case MetaMTAReceivedMailStatus::STATUS_DUPLICATE:
@@ -311,51 +380,6 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
         'text, and signatures are discarded and ignored.'));
   }
 
-  /**
-   * Load a concrete instance of the @{class:PhabricatorMailReceiver} which
-   * accepts this mail, if one exists.
-   */
-  private function loadReceiver() {
-    $receivers = id(new PhutilClassMapQuery())
-      ->setAncestorClass('PhabricatorMailReceiver')
-      ->setFilterMethod('isEnabled')
-      ->execute();
-
-    $accept = array();
-    foreach ($receivers as $key => $receiver) {
-      if ($receiver->canAcceptMail($this)) {
-        $accept[$key] = $receiver;
-      }
-    }
-
-    if (!$accept) {
-      throw new PhabricatorMetaMTAReceivedMailProcessingException(
-        MetaMTAReceivedMailStatus::STATUS_NO_RECEIVERS,
-        pht(
-          'Phabricator can not process this mail because no application '.
-          'knows how to handle it. Check that the address you sent it to is '.
-          'correct.'.
-          "\n\n".
-          '(No concrete, enabled subclass of PhabricatorMailReceiver can '.
-          'accept this mail.)'));
-    }
-
-    if (count($accept) > 1) {
-      $names = implode(', ', array_keys($accept));
-      throw new PhabricatorMetaMTAReceivedMailProcessingException(
-        MetaMTAReceivedMailStatus::STATUS_ABUNDANT_RECEIVERS,
-        pht(
-          'Phabricator is not able to process this mail because more than '.
-          'one application is willing to accept it, creating ambiguity. '.
-          'Mail needs to be accepted by exactly one receiving application.'.
-          "\n\n".
-          'Accepting receivers: %s.',
-          $names));
-    }
-
-    return head($accept);
-  }
-
   private function sendExceptionMail(
     Exception $ex,
     PhabricatorUser $viewer = null) {
@@ -434,4 +458,74 @@ EOBODY
       ));
   }
 
+  public function newFromAddress() {
+    $raw_from = $this->getHeader('From');
+
+    if (strlen($raw_from)) {
+      return new PhutilEmailAddress($raw_from);
+    }
+
+    return null;
+  }
+
+  private function getViewer() {
+    return PhabricatorUser::getOmnipotentUser();
+  }
+
+  /**
+   * Identify the sender's user account for a piece of received mail.
+   *
+   * Note that this method does not validate that the sender is who they say
+   * they are, just that they've presented some credential which corresponds
+   * to a recognizable user.
+   */
+  private function loadSender() {
+    $viewer = $this->getViewer();
+
+    // Try to identify the user based on their "From" address.
+    $from_address = $this->newFromAddress();
+    if ($from_address) {
+      $user = id(new PhabricatorPeopleQuery())
+        ->setViewer($viewer)
+        ->withEmails(array($from_address->getAddress()))
+        ->executeOne();
+      if ($user) {
+        return $user;
+      }
+    }
+
+    return null;
+  }
+
+  private function validateSender(PhabricatorUser $sender) {
+    $failure_reason = null;
+    if ($sender->getIsDisabled()) {
+      $failure_reason = pht(
+        'Your account ("%s") is disabled, so you can not interact with '.
+        'Phabricator over email.',
+        $sender->getUsername());
+    } else if ($sender->getIsStandardUser()) {
+      if (!$sender->getIsApproved()) {
+        $failure_reason = pht(
+          'Your account ("%s") has not been approved yet. You can not '.
+          'interact with Phabricator over email until your account is '.
+          'approved.',
+          $sender->getUsername());
+      } else if (PhabricatorUserEmail::isEmailVerificationRequired() &&
+               !$sender->getIsEmailVerified()) {
+        $failure_reason = pht(
+          'You have not verified the email address for your account ("%s"). '.
+          'You must verify your email address before you can interact '.
+          'with Phabricator over email.',
+          $sender->getUsername());
+      }
+    }
+
+    if ($failure_reason) {
+      throw new PhabricatorMetaMTAReceivedMailProcessingException(
+        MetaMTAReceivedMailStatus::STATUS_DISABLED_SENDER,
+        $failure_reason);
+    }
+  }
+
 }
diff --git a/src/applications/metamta/storage/__tests__/PhabricatorMetaMTAReceivedMailTestCase.php b/src/applications/metamta/storage/__tests__/PhabricatorMetaMTAReceivedMailTestCase.php
index 31a31b5ff2..2630a50feb 100644
--- a/src/applications/metamta/storage/__tests__/PhabricatorMetaMTAReceivedMailTestCase.php
+++ b/src/applications/metamta/storage/__tests__/PhabricatorMetaMTAReceivedMailTestCase.php
@@ -48,11 +48,15 @@ final class PhabricatorMetaMTAReceivedMailTestCase extends PhabricatorTestCase {
   }
 
   public function testDropUnreceivableMail() {
+    $user = $this->generateNewTestUser()
+      ->save();
+
     $mail = new PhabricatorMetaMTAReceivedMail();
     $mail->setHeaders(
       array(
         'Message-ID' => 'test@example.com',
         'To'         => 'does+not+exist@example.com',
+        'From'        => $user->loadPrimaryEmail()->getAddress(),
       ));
     $mail->setBodies(
       array(
@@ -70,10 +74,6 @@ final class PhabricatorMetaMTAReceivedMailTestCase extends PhabricatorTestCase {
   public function testDropUnknownSenderMail() {
     $this->setManiphestCreateEmail();
 
-    $env = PhabricatorEnv::beginScopedEnv();
-    $env->overrideEnvConfig('phabricator.allow-email-users', false);
-    $env->overrideEnvConfig('metamta.maniphest.default-public-author', null);
-
     $mail = new PhabricatorMetaMTAReceivedMail();
     $mail->setHeaders(
       array(
diff --git a/src/applications/paste/mail/PasteCreateMailReceiver.php b/src/applications/paste/mail/PasteCreateMailReceiver.php
index 992d1e60b5..844c5f1acc 100644
--- a/src/applications/paste/mail/PasteCreateMailReceiver.php
+++ b/src/applications/paste/mail/PasteCreateMailReceiver.php
@@ -9,7 +9,8 @@ final class PasteCreateMailReceiver
 
   protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
+    PhutilEmailAddress $target) {
+    $author = $this->getAuthor();
 
     $title = $mail->getSubject();
     if (!$title) {
@@ -26,18 +27,23 @@ final class PasteCreateMailReceiver
       ->setTransactionType(PhabricatorPasteTitleTransaction::TRANSACTIONTYPE)
       ->setNewValue($title);
 
-    $paste = PhabricatorPaste::initializeNewPaste($sender);
+    $paste = PhabricatorPaste::initializeNewPaste($author);
 
     $content_source = $mail->newContentSource();
 
     $editor = id(new PhabricatorPasteEditor())
-      ->setActor($sender)
+      ->setActor($author)
       ->setContentSource($content_source)
       ->setContinueOnNoEffect(true);
     $xactions = $editor->applyTransactions($paste, $xactions);
 
     $mail->setRelatedPHID($paste->getPHID());
 
+    $sender = $this->getSender();
+    if (!$sender) {
+      return;
+    }
+
     $subject_prefix =
       PhabricatorEnv::getEnvConfig('metamta.paste.subject-prefix');
     $subject = pht('You successfully created a paste.');
@@ -56,5 +62,4 @@ final class PasteCreateMailReceiver
       ->saveAndSend();
   }
 
-
 }
diff --git a/src/applications/paste/mail/PasteMailReceiver.php b/src/applications/paste/mail/PasteMailReceiver.php
index cb5a6e8982..f0b2f4674c 100644
--- a/src/applications/paste/mail/PasteMailReceiver.php
+++ b/src/applications/paste/mail/PasteMailReceiver.php
@@ -12,7 +12,7 @@ final class PasteMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'P');
+    $id = (int)substr($pattern, 1);
 
     return id(new PhabricatorPasteQuery())
       ->setViewer($viewer)
diff --git a/src/applications/phame/mail/PhamePostMailReceiver.php b/src/applications/phame/mail/PhamePostMailReceiver.php
index 3655e73906..3e2f493d3a 100644
--- a/src/applications/phame/mail/PhamePostMailReceiver.php
+++ b/src/applications/phame/mail/PhamePostMailReceiver.php
@@ -13,7 +13,7 @@ final class PhamePostMailReceiver
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)substr($pattern, 4);
+    $id = (int)substr($pattern, 1);
 
     return id(new PhamePostQuery())
       ->setViewer($viewer)
diff --git a/src/applications/pholio/mail/PholioMockMailReceiver.php b/src/applications/pholio/mail/PholioMockMailReceiver.php
index 09c0eb3051..13fdc559ec 100644
--- a/src/applications/pholio/mail/PholioMockMailReceiver.php
+++ b/src/applications/pholio/mail/PholioMockMailReceiver.php
@@ -12,7 +12,7 @@ final class PholioMockMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'M');
+    $id = (int)substr($pattern, 1);
 
     return id(new PholioMockQuery())
       ->setViewer($viewer)
diff --git a/src/applications/ponder/mail/PonderAnswerMailReceiver.php b/src/applications/ponder/mail/PonderAnswerMailReceiver.php
index d7269ac861..dfa252c4a1 100644
--- a/src/applications/ponder/mail/PonderAnswerMailReceiver.php
+++ b/src/applications/ponder/mail/PonderAnswerMailReceiver.php
@@ -12,7 +12,7 @@ final class PonderAnswerMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'ANSR');
+    $id = (int)substr($pattern, 4);
 
     return id(new PonderAnswerQuery())
       ->setViewer($viewer)
diff --git a/src/applications/ponder/mail/PonderQuestionCreateMailReceiver.php b/src/applications/ponder/mail/PonderQuestionCreateMailReceiver.php
index 1eb3269798..32669855ea 100644
--- a/src/applications/ponder/mail/PonderQuestionCreateMailReceiver.php
+++ b/src/applications/ponder/mail/PonderQuestionCreateMailReceiver.php
@@ -9,7 +9,8 @@ final class PonderQuestionCreateMailReceiver
 
   protected function processReceivedMail(
     PhabricatorMetaMTAReceivedMail $mail,
-    PhabricatorUser $sender) {
+    PhutilEmailAddress $target) {
+    $author = $this->getAuthor();
 
     $title = $mail->getSubject();
     if (!strlen($title)) {
@@ -26,18 +27,17 @@ final class PonderQuestionCreateMailReceiver
       ->setTransactionType(PonderQuestionTransaction::TYPE_CONTENT)
       ->setNewValue($mail->getCleanTextBody());
 
-    $question = PonderQuestion::initializeNewQuestion($sender);
+    $question = PonderQuestion::initializeNewQuestion($author);
 
     $content_source = $mail->newContentSource();
 
     $editor = id(new PonderQuestionEditor())
-      ->setActor($sender)
+      ->setActor($author)
       ->setContentSource($content_source)
       ->setContinueOnNoEffect(true);
     $xactions = $editor->applyTransactions($question, $xactions);
 
     $mail->setRelatedPHID($question->getPHID());
-
   }
 
 
diff --git a/src/applications/ponder/mail/PonderQuestionMailReceiver.php b/src/applications/ponder/mail/PonderQuestionMailReceiver.php
index 6388837af3..e68d6c0ecb 100644
--- a/src/applications/ponder/mail/PonderQuestionMailReceiver.php
+++ b/src/applications/ponder/mail/PonderQuestionMailReceiver.php
@@ -12,7 +12,7 @@ final class PonderQuestionMailReceiver extends PhabricatorObjectMailReceiver {
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)trim($pattern, 'Q');
+    $id = (int)substr($pattern, 1);
 
     return id(new PonderQuestionQuery())
       ->setViewer($viewer)
diff --git a/src/applications/slowvote/mail/PhabricatorSlowvoteMailReceiver.php b/src/applications/slowvote/mail/PhabricatorSlowvoteMailReceiver.php
index 78e608231f..7b7459d4c3 100644
--- a/src/applications/slowvote/mail/PhabricatorSlowvoteMailReceiver.php
+++ b/src/applications/slowvote/mail/PhabricatorSlowvoteMailReceiver.php
@@ -13,7 +13,7 @@ final class PhabricatorSlowvoteMailReceiver
   }
 
   protected function loadObject($pattern, PhabricatorUser $viewer) {
-    $id = (int)substr($pattern, 4);
+    $id = (int)substr($pattern, 1);
 
     return id(new PhabricatorSlowvoteQuery())
       ->setViewer($viewer)