Email rejection to "holding pen"

I agree with @fefrei, even spam. There’s a reason all modern email clients have a spam folder/trap, and not a black hole. Algorithms aren’t perfect. Same reason Akismet requests a staff review, and doesn’t just delete the message. If an email can’t automatically be added to a topic for any reason, staff should be able to see both why, and resolve the issue so it can be posted without another email being sent.