At work we currently use google biz apps. Which as the only IT guy I love and has been pretty much trouble free during my time at this company.
however for several reasons were considering moving to a internally hosted soluton.
the 3 driving factors for this are (in order)
1) some places that our employees work have blocked access to public Gmail and as a consequence our email is blocked as well 2) Privacy / security. we recently had a "incident" where someone would have sent something over email that they shouldn't have. If that had happened we may have been required to "quarantine" our email server which we obviously could not do with google biz apps. 3) lastly as always price. I'm disappointed with Google for not having tiered pricing (50 bucks a person/year for 1 user or 1000 users).
I'm almost 100% sure that Google doesn't offer it but if they had a network appliance that would offer all the same functionality but was physically in our office I would buy it in a second
I have looked at services like zimbra and other but they don't offer any hardware and I'm reluctant to buy a bunch of hardware for a service im not sure I like yet.
If anyone has any ideas one what a good trouble free solution for hosting our own mail is I would love to hear it.