I've asked them this before (but also include file hosting/web hosting) and it almost seemed to happen, but then things got pretty crazy/busy there. I think it's an overhead they don't want to hassle with.
I suggest USA.NET for e-mail hosting. They have the best spam filter I've ever seen!
i'm leaning towards simplehost.com. while i'm sure they are not the cheapest, anything below $7/mo is really splitting hairs. they also offer unlimited disk space(strange indeed) and unlimited POP3 accounts. not too shabby eh¿?