We've been on Apptix for a couple of years and in the last six months have had a huge number of problems. Not the least of which are a support ticketing system that has no customer portal so the process of tickets is opaque. The thing that finally broke me was a two hour outage of outgoing email in the middle of a business day at their filter partner. We noticed a problem only because our support system stopped getting emails forwarded to it. The ticket at Apptix took three days to get an answer on and it was, to paraphrase, 'we know that from zero to 100 percent of outgoing email was lost during that period but did it is not our policy to notify customers when something like this happens. It wasn't us, it was our filtering partner.' I escalated the issue to their sales team and their VP of customer support without getting a reply.
Tried Google Apps but got a lot of hate on their conversation threading in the web view. The way they apply filters is also semi-random. Doesn't seem like it would be, but that is what their support finally admitted after what my account showed didn't line up with how they claimed filters would work.
Am now looking at other hosted exchange providers. I'll take a look at Sherweb and Rackspace. Are people happy there, any other suggestions? We're ready to pay real money for reliable service and solid support.