When we fail to process mail, tell the user about it

Summary:
Ref T4371. Ref T4699. Fixes T3994.

Currently, we're very conservative about sending errors back to users. A concern I had about this was that mistakes could lead to email loops, massive amounts of email spam, etc. Because of this, I was pretty hesitant about replying to email with more email when I wrote this stuff.

However, this was a long time ago. We now have Message-ID deduplication, "X-Phabricator-Sent-This-Mail", generally better mail infrastructure, and rate limiting. Together, these mechanisms should reasonably prevent anything crazy (primarily, infinite email loops) from happening.

Thus:

  - When we hit any processing error after receiving a mail, try to send the author a reply with details about what went wrong. These are limited to 6 per hour per address.
  - Rewrite most of the errors to be more detailed and informative.
  - Rewrite most of the errors in a user-facing voice ("You sent this mail..." instead of "This mail was sent..").
  - Remove the redundant, less sophisticated code which does something similar in Differential.

Test Plan:
  - Using `scripts/mail/mail_receiver.php`, artificially received a pile of mail.
  - Hit a bunch of different errors.
  - Saw reasonable error mail get sent to me.
  - Saw other reasonable error mail get rate limited.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T3994, T4371, T4699

Differential Revision: https://secure.phabricator.com/D8692

src/__phutil_library_map__.php

@@ -371,7 +371,6 @@ phutil_register_library_map(array(
     'DifferentialDoorkeeperRevisionFeedStoryPublisher' => 'applications/differential/doorkeeper/DifferentialDoorkeeperRevisionFeedStoryPublisher.php',
     'DifferentialDraft' => 'applications/differential/storage/DifferentialDraft.php',
     'DifferentialEditPolicyField' => 'applications/differential/customfield/DifferentialEditPolicyField.php',
-    'DifferentialExceptionMail' => 'applications/differential/mail/DifferentialExceptionMail.php',
     'DifferentialFieldParseException' => 'applications/differential/exception/DifferentialFieldParseException.php',
     'DifferentialFieldValidationException' => 'applications/differential/exception/DifferentialFieldValidationException.php',
     'DifferentialGetWorkingCopy' => 'applications/differential/DifferentialGetWorkingCopy.php',
@@ -398,7 +397,6 @@ phutil_register_library_map(array(
     'DifferentialLintStatus' => 'applications/differential/constants/DifferentialLintStatus.php',
     'DifferentialLocalCommitsView' => 'applications/differential/view/DifferentialLocalCommitsView.php',
     'DifferentialMail' => 'applications/differential/mail/DifferentialMail.php',
-    'DifferentialMailPhase' => 'applications/differential/constants/DifferentialMailPhase.php',
     'DifferentialManiphestTasksField' => 'applications/differential/customfield/DifferentialManiphestTasksField.php',
     'DifferentialPHIDTypeDiff' => 'applications/differential/phid/DifferentialPHIDTypeDiff.php',
     'DifferentialPHIDTypeRevision' => 'applications/differential/phid/DifferentialPHIDTypeRevision.php',
@@ -1693,6 +1691,7 @@ phutil_register_library_map(array(
     'PhabricatorMetaMTADAO' => 'applications/metamta/storage/PhabricatorMetaMTADAO.php',
     'PhabricatorMetaMTAEmailBodyParser' => 'applications/metamta/parser/PhabricatorMetaMTAEmailBodyParser.php',
     'PhabricatorMetaMTAEmailBodyParserTestCase' => 'applications/metamta/parser/__tests__/PhabricatorMetaMTAEmailBodyParserTestCase.php',
+    'PhabricatorMetaMTAErrorMailAction' => 'applications/metamta/action/PhabricatorMetaMTAErrorMailAction.php',
     'PhabricatorMetaMTAMail' => 'applications/metamta/storage/PhabricatorMetaMTAMail.php',
     'PhabricatorMetaMTAMailBody' => 'applications/metamta/view/PhabricatorMetaMTAMailBody.php',
     'PhabricatorMetaMTAMailBodyTestCase' => 'applications/metamta/view/__tests__/PhabricatorMetaMTAMailBodyTestCase.php',
@@ -2952,7 +2951,6 @@ phutil_register_library_map(array(
     'DifferentialDoorkeeperRevisionFeedStoryPublisher' => 'DoorkeeperFeedStoryPublisher',
     'DifferentialDraft' => 'DifferentialDAO',
     'DifferentialEditPolicyField' => 'DifferentialCoreCustomField',
-    'DifferentialExceptionMail' => 'DifferentialMail',
     'DifferentialFieldParseException' => 'Exception',
     'DifferentialFieldValidationException' => 'Exception',
     'DifferentialGitSVNIDField' => 'DifferentialCustomField',
@@ -4487,6 +4485,7 @@ phutil_register_library_map(array(
     'PhabricatorMetaMTAController' => 'PhabricatorController',
     'PhabricatorMetaMTADAO' => 'PhabricatorLiskDAO',
     'PhabricatorMetaMTAEmailBodyParserTestCase' => 'PhabricatorTestCase',
+    'PhabricatorMetaMTAErrorMailAction' => 'PhabricatorSystemAction',
     'PhabricatorMetaMTAMail' => 'PhabricatorMetaMTADAO',
     'PhabricatorMetaMTAMailBodyTestCase' => 'PhabricatorTestCase',
     'PhabricatorMetaMTAMailTestCase' => 'PhabricatorTestCase',

src/applications/differential/constants/DifferentialMailPhase.php

@@ -1,9 +0,0 @@
-<?php
-
-final class DifferentialMailPhase {
-
-  const WELCOME = 1;
-  const UPDATE = 2;
-  const COMMENT = 3;
-
-}

src/applications/differential/mail/DifferentialExceptionMail.php

@@ -1,45 +0,0 @@
-<?php
-
-final class DifferentialExceptionMail extends DifferentialMail {
-
-  public function __construct(
-    DifferentialRevision $revision,
-    Exception $exception,
-    $original_body) {
-
-    $this->revision = $revision;
-    $this->exception = $exception;
-    $this->originalBody = $original_body;
-  }
-
-  protected function renderBody() {
-    // Never called since buildBody() is overridden.
-  }
-
-  protected function renderSubject() {
-    return "Exception: unable to process your mail request";
-  }
-
-  protected function renderVaryPrefix() {
-    return '';
-  }
-
-  protected function buildBody() {
-    $exception = $this->exception;
-    $original_body = $this->originalBody;
-
-    $message = $exception->getMessage();
-
-    return <<<EOBODY
-Your request failed because an exception was encoutered while processing it:
-
-EXCEPTION: {$message}
-
--- Original Body -------------------------------------------------------------
-
-{$original_body}
-
-EOBODY;
-  }
-
-}

src/applications/differential/mail/DifferentialReplyHandler.php

@@ -169,25 +169,7 @@ class DifferentialReplyHandler extends PhabricatorMailReplyHandler {
       $editor->setContentSource($content_source);
     }
 
-    try {
+    $editor->applyTransactions($this->getMailReceiver(), $xactions);
-      $editor->applyTransactions($this->getMailReceiver(), $xactions);
-    } catch (Exception $ex) {
-      if ($this->receivedMail) {
-        $error_body = $this->receivedMail->getRawTextBody();
-      } else {
-        $error_body = $body;
-      }
-      $exception_mail = new DifferentialExceptionMail(
-        $this->getMailReceiver(),
-        $ex,
-        $error_body);
-
-      $exception_mail->setActor($this->getActor());
-      $exception_mail->setToPHIDs(array($this->getActor()->getPHID()));
-      $exception_mail->send();
-
-      throw $ex;
-    }
   }
 
 }

src/applications/metamta/action/PhabricatorMetaMTAErrorMailAction.php

@@ -0,0 +1,13 @@
+<?php
+
+final class PhabricatorMetaMTAErrorMailAction extends PhabricatorSystemAction {
+
+  public function getActionConstant() {
+    return 'email.error';
+  }
+
+  public function getScoreThreshold() {
+    return 6 / phutil_units('1 hour in seconds');
+  }
+
+}

src/applications/metamta/constants/MetaMTAReceivedMailStatus.php

@@ -16,4 +16,23 @@ final class MetaMTAReceivedMailStatus
   const STATUS_HASH_MISMATCH        = 'err:bad-hash';
   const STATUS_UNHANDLED_EXCEPTION  = 'err:exception';
 
+  public static function getHumanReadableName($status) {
+    $map = array(
+      self::STATUS_DUPLICATE => pht('Duplicate Message'),
+      self::STATUS_FROM_PHABRICATOR => pht('Phabricator Mail'),
+      self::STATUS_NO_RECEIVERS => pht('No Receivers'),
+      self::STATUS_ABUNDANT_RECEIVERS => pht('Multiple Receivers'),
+      self::STATUS_UNKNOWN_SENDER => pht('Unknown Sender'),
+      self::STATUS_DISABLED_SENDER => pht('Disabled Sender'),
+      self::STATUS_NO_PUBLIC_MAIL => pht('No Public Mail'),
+      self::STATUS_USER_MISMATCH => pht('User Mismatch'),
+      self::STATUS_POLICY_PROBLEM => pht('Policy Error'),
+      self::STATUS_NO_SUCH_OBJECT => pht('No Such Object'),
+      self::STATUS_HASH_MISMATCH => pht('Bad Address'),
+      self::STATUS_UNHANDLED_EXCEPTION => pht('Unhandled Exception'),
+    );
+
+    return idx($map, $status, pht('Processing Exception'));
+  }
+
 }

src/applications/metamta/receiver/PhabricatorMailReceiver.php

@@ -19,12 +19,32 @@ abstract class PhabricatorMailReceiver {
     PhabricatorMetaMTAReceivedMail $mail,
     PhabricatorUser $sender) {
 
-    if (!$sender->isUserActivated()) {
+    $failure_reason = null;
+    if ($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,
-        pht(
+        $failure_reason);
-          "Sender '%s' does not have an activated user account.",
-          $sender->getUsername()));
     }
   }
 
@@ -46,33 +66,34 @@ abstract class PhabricatorMailReceiver {
       return $user;
     } else {
       $reasons[] = pht(
-        "The email was sent from '%s', but this address does not correspond ".
+        'This email was sent from "%s", but that address is not recognized by '.
-        "to any user account.",
+        'Phabricator and does not correspond to any known user account.',
         $raw_from);
     }
 
     // If we missed on "From", try "Reply-To" if we're configured for it.
-    $reply_to_key = 'metamta.insecure-auth-with-reply-to';
+    $raw_reply_to = $mail->getHeader('Reply-To');
-    $allow_reply_to = PhabricatorEnv::getEnvConfig($reply_to_key);
+    if (strlen($raw_reply_to)) {
-    if ($allow_reply_to) {
+      $reply_to_key = 'metamta.insecure-auth-with-reply-to';
-      $raw_reply_to = $mail->getHeader('Reply-To');
+      $allow_reply_to = PhabricatorEnv::getEnvConfig($reply_to_key);
-      $reply_to = self::getRawAddress($raw_reply_to);
+      if ($allow_reply_to) {
+        $reply_to = self::getRawAddress($raw_reply_to);
 
-      $user = PhabricatorUser::loadOneWithEmailAddress($reply_to);
+        $user = PhabricatorUser::loadOneWithEmailAddress($reply_to);
-      if ($user) {
+        if ($user) {
-        return $user;
+          return $user;
+        } else {
+          $reasons[] = pht(
+            'Phabricator is configured to authenticate users using the '.
+            '"Reply-To" header, but the reply address ("%s") on this '.
+            'message does not correspond to any known user account.',
+            $raw_reply_to);
+        }
       } else {
         $reasons[] = pht(
-          "Phabricator is configured to try to authenticate users using ".
+          '(Phabricator is not configured to authenticate users using the '.
-          "'Reply-To', but the reply to address ('%s') does not correspond ".
+          '"Reply-To" header, so it was ignored.)');
-          "to any user account.",
-          $raw_reply_to);
       }
-    } else {
-      $reasons[] = pht(
-        "Phabricator is not configured to authenticate users using ".
-        "'Reply-To' (`metamta.insecure-auth-with-reply-to`), so the ".
-        "'Reply-To' header was not examined.");
     }
 
     // If we don't know who this user is, load or create an external user
@@ -82,7 +103,7 @@ abstract class PhabricatorMailReceiver {
     if ($allow_email_users) {
       $from_obj = new PhutilEmailAddress($from);
       $xuser = id(new PhabricatorExternalAccountQuery())
-        ->setViewer($user)
+        ->setViewer(PhabricatorUser::getOmnipotentUser())
         ->withAccountTypes(array('email'))
         ->withAccountDomains(array($from_obj->getDomainName(), 'self'))
         ->withAccountIDs(array($from_obj->getAddress()))
@@ -90,15 +111,19 @@ abstract class PhabricatorMailReceiver {
       return $xuser->getPhabricatorUser();
     } else {
       $reasons[] = pht(
-        "Phabricator is not configured to allow unknown external users to ".
+        'Phabricator is also not configured to allow unknown external users '.
-        "send mail to the system using just an email address ".
+        'to send mail to the system using just an email address.');
-        "(`phabricator.allow-email-users`), so an implicit external acount ".
+      $reasons[] = pht(
-        "could not be created.");
+        'To interact with Phabricator, add this address ("%s") to your '.
+        'account.',
+        $raw_from);
     }
 
+    $reasons = implode("\n\n", $reasons);
+
     throw new PhabricatorMetaMTAReceivedMailProcessingException(
       MetaMTAReceivedMailStatus::STATUS_UNKNOWN_SENDER,
-      pht('Unknown sender: %s', implode(' ', $reasons)));
+      $reasons);
   }
 
   /**

src/applications/metamta/receiver/PhabricatorObjectMailReceiver.php

@@ -55,6 +55,7 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
     parent::validateSender($mail, $sender);
 
     $parts = $this->matchObjectAddressInMail($mail);
+    $pattern = $parts['pattern'];
 
     try {
       $object = $this->loadObjectFromMail($mail, $sender);
@@ -62,8 +63,9 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
       throw new PhabricatorMetaMTAReceivedMailProcessingException(
         MetaMTAReceivedMailStatus::STATUS_POLICY_PROBLEM,
         pht(
-          "This mail is addressed to an object you are not permitted ".
+          'This mail is addressed to an object ("%s") you do not have '.
-          "to see: %s",
+          'permission to see: %s',
+          $pattern,
           $policy_exception->getMessage()));
     }
 
@@ -71,9 +73,9 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
       throw new PhabricatorMetaMTAReceivedMailProcessingException(
         MetaMTAReceivedMailStatus::STATUS_NO_SUCH_OBJECT,
         pht(
-          "This mail is addressed to an object ('%s'), but that object ".
+          'This mail is addressed to an object ("%s"), but that object '.
-          "does not exist.",
+          'does not exist.',
-          $parts['pattern']));
+          $pattern));
     }
 
     $sender_identifier = $parts['sender'];
@@ -83,8 +85,12 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
         throw new PhabricatorMetaMTAReceivedMailProcessingException(
           MetaMTAReceivedMailStatus::STATUS_NO_PUBLIC_MAIL,
           pht(
-            "This mail is addressed to an object's public address, but ".
+            'This mail is addressed to the public email address of an object '.
-            "public replies are not enabled (`metamta.public-replies`)."));
+            '("%s"), but public replies are not enabled on this Phabricator '.
+            'install. An administrator may have recently disabled this '.
+            'setting, or you may have replied to an old message. Try '.
+            'replying to a more recent message instead.',
+            $pattern));
       }
       $check_phid = $object->getPHID();
     } else {
@@ -92,9 +98,12 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
         throw new PhabricatorMetaMTAReceivedMailProcessingException(
           MetaMTAReceivedMailStatus::STATUS_USER_MISMATCH,
           pht(
-            "This mail is addressed to an object's private address, but ".
+            'This mail is addressed to the private email address of an object '.
-            "the sending user and the private address owner are not the ".
+            '("%s"), but you are not the user who is authorized to use the '.
-            "same user."));
+            'address you sent mail to. Each private address is unique to the '.
+            'user who received the original mail. Try replying to a message '.
+            'which was sent directly to you instead.',
+            $pattern));
       }
       $check_phid = $sender->getPHID();
     }
@@ -105,8 +114,10 @@ abstract class PhabricatorObjectMailReceiver extends PhabricatorMailReceiver {
       throw new PhabricatorMetaMTAReceivedMailProcessingException(
         MetaMTAReceivedMailStatus::STATUS_HASH_MISMATCH,
         pht(
-          "The hash in this object's address does not match the expected ".
+          'This mail is addressed to an object ("%s"), but the address is '.
-          "value."));
+          'not correct (the security hash is wrong). Check that the address '.
+          'is correct.',
+          $pattern));
     }
   }
 

src/applications/metamta/storage/PhabricatorMetaMTAMail.php

@@ -222,6 +222,15 @@ final class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
     return $this;
   }
 
+  public function setIsErrorEmail($is_error) {
+    $this->setParam('is-error', $is_error);
+    return $this;
+  }
+
+  public function getIsErrorEmail() {
+    return $this->getParam('is-error', false);
+  }
+
   public function getWorkerTaskID() {
     return $this->getParam('worker-task');
   }
@@ -549,6 +558,19 @@ final class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
         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();
+        }
+      }
+
       $mailer->addHeader('X-Phabricator-Sent-This-Message', 'Yes');
       $mailer->addHeader('X-Mail-Transport-Agent', 'MetaMTA');
 
@@ -839,5 +861,17 @@ final class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
     return $actors;
   }
 
+  private function shouldRateLimitMail(array $all_recipients) {
+    try {
+      PhabricatorSystemActionEngine::willTakeAction(
+        $all_recipients,
+        new PhabricatorMetaMTAErrorMailAction(),
+        1);
+      return false;
+    } catch (PhabricatorSystemActionRateLimitException $ex) {
+      return true;
+    }
+  }
+
 
 }

src/applications/metamta/storage/PhabricatorMetaMTAReceivedMail.php

@@ -102,12 +102,25 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
 
       $receiver->receiveMail($this, $sender);
     } catch (PhabricatorMetaMTAReceivedMailProcessingException $ex) {
+      switch ($ex->getStatusCode()) {
+        case MetaMTAReceivedMailStatus::STATUS_DUPLICATE:
+        case MetaMTAReceivedMailStatus::STATUS_FROM_PHABRICATOR:
+          // Don't send an error email back in these cases, since they're
+          // very unlikely to be the sender's fault.
+          break;
+        default:
+          $this->sendExceptionMail($ex);
+          break;
+      }
+
       $this
         ->setStatus($ex->getStatusCode())
         ->setMessage($ex->getMessage())
         ->save();
       return $this;
     } catch (Exception $ex) {
+      $this->sendExceptionMail($ex);
+
       $this
         ->setStatus(MetaMTAReceivedMailStatus::STATUS_UNHANDLED_EXCEPTION)
         ->setMessage(pht('Unhandled Exception: %s', $ex->getMessage()))
@@ -169,8 +182,9 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
 
     throw new PhabricatorMetaMTAReceivedMailProcessingException(
       MetaMTAReceivedMailStatus::STATUS_FROM_PHABRICATOR,
-      "Ignoring email with 'X-Phabricator-Sent-This-Message' header to avoid ".
+      pht(
-      "loops.");
+        "Ignoring email with 'X-Phabricator-Sent-This-Message' header to ".
+        "avoid loops."));
   }
 
   /**
@@ -203,8 +217,8 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
       return;
     }
 
-    $message = sprintf(
+    $message = pht(
-      'Ignoring email with message id hash "%s" that has been seen %d '.
+      'Ignoring email with "Message-ID" hash "%s" that has been seen %d '.
       'times, including this message.',
       $message_id_hash,
       $messages_count);
@@ -237,18 +251,70 @@ final class PhabricatorMetaMTAReceivedMail extends PhabricatorMetaMTADAO {
     if (!$accept) {
       throw new PhabricatorMetaMTAReceivedMailProcessingException(
         MetaMTAReceivedMailStatus::STATUS_NO_RECEIVERS,
-        "No concrete, enabled subclasses of `PhabricatorMailReceiver` can ".
+        pht(
-        "accept this mail.");
+          '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,
-        "More than one `PhabricatorMailReceiver` claims to accept this mail.");
+        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) {
+    $from = $this->getHeader('from');
+    if (!strlen($from)) {
+      return;
+    }
+
+    if ($ex instanceof PhabricatorMetaMTAReceivedMailProcessingException) {
+      $status_code = $ex->getStatusCode();
+      $status_name = MetaMTAReceivedMailStatus::getHumanReadableName(
+        $status_code);
+
+      $title = pht('Error Processing Mail (%s)', $status_name);
+      $description = $ex->getMessage();
+    } else {
+      $title = pht('Error Processing Mail (%s)', get_class($ex));
+      $description = pht('%s: %s', get_class($ex), $ex->getMessage());
+    }
+
+    $body = pht(<<<EOBODY
+Your email to Phabricator was not processed, because an error occurred while
+trying to handle it:
+
+%s
+
+-- Original Message Body -----------------------------------------------------
+
+%s
+
+EOBODY
+,
+      wordwrap($description, 78),
+      $this->getRawTextBody());
+
+    $mail = id(new PhabricatorMetaMTAMail())
+      ->setIsErrorEmail(true)
+      ->setSubject($title)
+      ->addRawTos(array($from))
+      ->setBody($body)
+      ->saveAndSend();
+  }
+
 }

src/applications/people/storage/PhabricatorUser.php

@@ -90,6 +90,18 @@ final class PhabricatorUser
     return true;
   }
 
+  /**
+   * Returns `true` if this is a standard user who is logged in. Returns `false`
+   * for logged out, anonymous, or external users.
+   *
+   * @return bool `true` if the user is a standard user who is logged in with
+   *              a normal session.
+   */
+  public function getIsStandardUser() {
+    $type_user = PhabricatorPeoplePHIDTypeUser::TYPECONST;
+    return $this->getPHID() && (phid_get_type($this->getPHID()) == $type_user);
+  }
+
   public function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,

src/applications/system/engine/PhabricatorSystemActionEngine.php

@@ -20,7 +20,9 @@ final class PhabricatorSystemActionEngine extends Phobject {
       }
     }
 
-    self::recordAction($actors, $action, $score);
+    $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+      self::recordAction($actors, $action, $score);
+    unset($unguarded);
   }
 
   public static function loadBlockedActors(