diff --git a/src/applications/maniphest/storage/ManiphestTransaction.php b/src/applications/maniphest/storage/ManiphestTransaction.php
--- a/src/applications/maniphest/storage/ManiphestTransaction.php
+++ b/src/applications/maniphest/storage/ManiphestTransaction.php
@@ -903,6 +903,7 @@
         $tags[] = self::MAILTAG_OWNER;
         break;
       case self::TYPE_CCS:
+      case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $tags[] = self::MAILTAG_CC;
         break;
       case PhabricatorTransactions::TYPE_EDGE: