When I send the email to inbox@app.trello.com I get the reply:
It looks like you are trying to use Trello’s email-to-board feature, which is great! The only problem is, it looks like the card ********** is in an archived list (Emails). Whoops!
Your email is still being forwarded to that card.
I can't figure out how to get it to stop trying to send it to a board.