My partners are currently setting up on 1and1 and love it. The email server has a high latency time, but works flawlessly.

We were using Terrasite (windows only), which were good, but high priced if you exceeded their bandwith. Cruznet.net (unix only) has unlimited bandwidth for only $30/month, but the mail is not the most reliable thing, and they have no control panels, you have to call them for everything.