This is easier to read for me. No early return

app/workers/email_receiver_worker.rb

@@ -21,36 +21,35 @@ class EmailReceiverWorker
     return unless raw.present?
 
     can_retry = false
-    reason = nil
-
-    case e
-    when Gitlab::Email::UnknownIncomingEmail
-      reason = "We couldn't figure out what the email is for."
-    when Gitlab::Email::SentNotificationNotFoundError
-      reason = "We couldn't figure out what the email is in reply to. Please create your comment through the web interface."
-    when Gitlab::Email::ProjectNotFound
-      reason = "We couldn't find the project. Please check if there's any typo."
-    when Gitlab::Email::EmptyEmailError
-      can_retry = true
-      reason = "It appears that the email is blank. Make sure your reply is at the top of the email, we can't process inline replies."
-    when Gitlab::Email::AutoGeneratedEmailError
-      reason = "The email was marked as 'auto generated', which we can't accept. Please create your comment through the web interface."
-    when Gitlab::Email::UserNotFoundError
-      reason = "We couldn't figure out what user corresponds to the email. Please create your comment through the web interface."
-    when Gitlab::Email::UserBlockedError
-      reason = "Your account has been blocked. If you believe this is in error, contact a staff member."
-    when Gitlab::Email::UserNotAuthorizedError
-      reason = "You are not allowed to perform this action. If you believe this is in error, contact a staff member."
-    when Gitlab::Email::NoteableNotFoundError
-      reason = "The thread you are replying to no longer exists, perhaps it was deleted? If you believe this is in error, contact a staff member."
-    when Gitlab::Email::InvalidNoteError,
-         Gitlab::Email::InvalidIssueError
-      can_retry = true
-      reason = e.message
-    else
-      return
+    reason =
+      case e
+      when Gitlab::Email::UnknownIncomingEmail
+        "We couldn't figure out what the email is for."
+      when Gitlab::Email::SentNotificationNotFoundError
+        "We couldn't figure out what the email is in reply to. Please create your comment through the web interface."
+      when Gitlab::Email::ProjectNotFound
+        "We couldn't find the project. Please check if there's any typo."
+      when Gitlab::Email::EmptyEmailError
+        can_retry = true
+        "It appears that the email is blank. Make sure your reply is at the top of the email, we can't process inline replies."
+      when Gitlab::Email::AutoGeneratedEmailError
+        "The email was marked as 'auto generated', which we can't accept. Please create your comment through the web interface."
+      when Gitlab::Email::UserNotFoundError
+        "We couldn't figure out what user corresponds to the email. Please create your comment through the web interface."
+      when Gitlab::Email::UserBlockedError
+        "Your account has been blocked. If you believe this is in error, contact a staff member."
+      when Gitlab::Email::UserNotAuthorizedError
+        "You are not allowed to perform this action. If you believe this is in error, contact a staff member."
+      when Gitlab::Email::NoteableNotFoundError
+        "The thread you are replying to no longer exists, perhaps it was deleted? If you believe this is in error, contact a staff member."
+      when Gitlab::Email::InvalidNoteError,
+           Gitlab::Email::InvalidIssueError
+        can_retry = true
+        e.message
+      end
+
+    if reason
+      EmailRejectionMailer.rejection(reason, raw, can_retry).deliver_later
     end
-
-    EmailRejectionMailer.rejection(reason, raw, can_retry).deliver_later
   end
 end