Why not run your own mail server? Outbound deliverability is a pain. You can't just install an SMTP server package and go -- you need to think about DomainKeys, SPF, DKIM, Sender-ID, monitoring realtime blacklists for your IP, etc. That's a whole job unto itself and is worth paying a couple bucks for someone else to do it.
There is an option for SLA with a paid Google Apps account. Last I checked it was $50/year, but comes with much larger inbox (25G at Google vs. 10G max at Rackspace). Also better integration and push notifications on mobile for Google, if you care about that.
Rackspace Mail for mail.
Why not run your own mail server? Outbound deliverability is a pain. You can't just install an SMTP server package and go -- you need to think about DomainKeys, SPF, DKIM, Sender-ID, monitoring realtime blacklists for your IP, etc. That's a whole job unto itself and is worth paying a couple bucks for someone else to do it.