A big "Me too" here...
Ever since I switched to dreamhost a couple months ago, my users (who use IMAP) have been ready to bite my head off. There's tons of stories about lost email too. I prepaid for a year of the code monster, and am now thinking about asking for a refund since it's clear they're not capable of running a mail server.
I left my UML provider because of the lack of disk performance/size, which are now minor complaints compared to this email stupidity. I've opened several tickets that all get closed with a form reply right after I open them. I keep asking them how many IMAP connections their servers allow to be cached so I can at least optimize that, but nobody in their tech support section is capable of hunting down an admin to get the answer.
That said, web space has been fine, which I mainly use for a few gigabyte large personal photo gallery. There was a mysql issue, but it was minor compared to this. Does anybody know of a good IMAP/POP/Webmail email provider that can host multiple domains? I'm willing to pay a reasonable fee, but I want something reliable. I'm not looking for Joe Wannabe's single coloed box, but something that uses words like 'cluster', 'failover', 'backed up', etc.