Well that sucks. I hope the venting helps. Possibly if you shared some of the specifics, we might could help get you back in business.
What cluster are you on and what is your mail server? Is your email IMAP, POP3, webmail? Are all those options inoperative, or just one or another of them? Can you send but not receive, or is it the other way around, or can you do neither? Can you log into the shell, and have you tried to see if you can reach your email via mutt/pine? Have you tried to see if email forwarding is working (might be a workaround while DH deals with your issue)?
The answers to some of those questions would go a long way to helping narrow down the problem, getting you a temporary workaround in place, or even helping identify the problem for the DreamHost techs.
At any rate, if there is anything anyone here can do to try to help you, let us know, ok?