This problem has plagued me for all of the Mac OS X betas I've installed on one of my iBooks, but since it wasn't my main machine, I haven't given it much worry. I recently got a new PowerBook, which came with 10.0.3 preinstalled, and was pleased to find that this problem didn't exist. I had a bad run in with 10.1 over the weekend, so I reinstalled the OS, many times in fact, and the problem is back :-( Since I backed up my account and restored it after the reinstall, I assume the problem lies outside of my mail preferences, since they're the same as before.
The problem is that while I'm using my home AirPort network, Mail
displays an alert panel when getting new mail saying "Fetch Error - Couldn't connect to POP host named ...". If I simply change the network
preferences to use the built-in Ethernet instead, Mail works fine.
Thanks in advance.