diff --git a/src/applications/metamta/parser/PhabricatorMetaMTAEmailBodyParser.php b/src/applications/metamta/parser/PhabricatorMetaMTAEmailBodyParser.php
index a53d9bf089..7ee2e02485 100644
--- a/src/applications/metamta/parser/PhabricatorMetaMTAEmailBodyParser.php
+++ b/src/applications/metamta/parser/PhabricatorMetaMTAEmailBodyParser.php
@@ -103,6 +103,13 @@ final class PhabricatorMetaMTAEmailBodyParser {
       '',
       $body);
 
+    // Mailbox seems to make an attempt to comply with the "standard" but
+    // omits the leading newline and uses an em dash?
+    $body = preg_replace(
+      "/\s*\xE2\x80\x94 \nSent from Mailbox\s*\z/su",
+      '',
+      $body);
+
     // HTC Mail application (mobile)
     $body = preg_replace(
       '/^\s*^Sent from my HTC smartphone.*/sm',
diff --git a/src/applications/metamta/parser/__tests__/PhabricatorMetaMTAEmailBodyParserTestCase.php b/src/applications/metamta/parser/__tests__/PhabricatorMetaMTAEmailBodyParserTestCase.php
index 4a9c2cc845..94473f498c 100644
--- a/src/applications/metamta/parser/__tests__/PhabricatorMetaMTAEmailBodyParserTestCase.php
+++ b/src/applications/metamta/parser/__tests__/PhabricatorMetaMTAEmailBodyParserTestCase.php
@@ -66,6 +66,7 @@ EOEMAIL;
 
   private function getEmailBodies() {
     $trailing_space = ' ';
+    $emdash = "\xE2\x80\x94";
 
     return array(
 <<<EOEMAIL
@@ -176,6 +177,11 @@ OKAY
 > -----Original Message-----
 >
 > ...
+EOMAIL
+,
+<<<EOMAIL
+OKAY {$emdash}{$trailing_space}
+Sent from Mailbox
 EOMAIL
     );
   }