If you are seeing this behaviour, please flush your DNS cache. Or if you're still accessing the webserver via the old IP, do that too. You should see much better performance - both in speed and reliability - as soon as you're seeing the new IP addresses.
If you do this and still can't talk to the mail server - like, say, all AT&T customers as far as we can tell - please switch to "mailx.murkworks.net" which is a new name introduced and therefore must be freshly looked up, because it can't be in your cache. That'll connect you to newmoon (the mail server) over the new pipes.
We'd've taken more time and made newmoon support both IPs except we were losing 40% of packets over the DSL again yesterday - burn in hell, Pioneer - and we just said fukkit, let's go. Really, this isn't going too badly; I wasn't even sure we'd be able to support both IP sets on the LAN like we are, because of questions about routing on the Comcast side, but turns out their little router box is smarter than they thought, and it works great! If newmoon had the right kernel, this would've been utterly transparent. As it is, this isn't too bad, and is moving reasonably quickly.
More as we have it...