Another option outside of getting a VPS is to get a Postini account and use them as a smarthost. Postini (or Google if you will) has a good reputation out there and you'll find much less mail blocked as a result. They also provide good inbound spam blocking services which you'll need eventually if you don't know.

Jungledisk was aquired by Rackspace some time ago. You can abandon S3 storage for Rackspace Cloudfiles using Jungledisk if you don't like Amazon. It also happens to be cheaper.