It actually didn’t used to be this way. Email used to be very stable at DreamHost. It has gotten worse over the last year or so. Strangely, this most recent batch of email problems has been a combination of two things.
The first is that the spunky cluster suffered from a password file corruption. This is basically the problem that keeps coming up and is a direct result of our having grown so large, so quickly.
The second is that on our swarthy cluster, our new beta authentication system (which use a database backend rather than a password file) got tens of thousands of domains wiped from the database. This was disappointing since this beta system was intended to resolve our growing pains with the original system mentioned above.
Our admins are still investigating the cause and we’re confident we can get it back on track, and lead DreamHost back to stable, reliable email service again. I personally believe our future depends on it.