DreamHost is dropping support for Catch-All mailboxes
Demerit's comments probably constitute the best answer available. It's a loss in flexibility and functionality compared to being able to use a catch-all mailbox, but it's probably as good as it gets, given the situation. I may experiment with SendGrid, but I'm not impressed with them so far. It's a public company that makes it difficult to ask a question. I could only ask a question after I signed up with them.  It was answered by someone who just googled SendGrid CiviCRM and came up with a few fairly worthless links.