I left DreamHost just in time:

We’re no longer allowing (new) FTP/SHELL users to have an email address associated with them.
[…]
Fortunately, this change should be more or less invisible to everybody! The only thing lost is the ability to see and manipulate your mail files via FTP/Shell… (and even that is only for new users from now on). Whoop-dee-do, I say!

Right, why would anyone want to use their own SpamAssassin, procmail, or a Unix mail client? I never had a problem with overselling at Dreamhost — in fact, I’d go so far as to say that I’m happy to take advantage of it — but I don’t think that’s their problem. I think they’ve just let themselves grow until they’re deep over their heads.

(And yes, that doesn’t affect existing shell accounts there, but I imagine that’s just a matter of time, because it’s not like running two parallel mail architectures is going to help them much.)