I plan to replace Mac OS X Server on my B&W G3 with Mandrake LinuxPPC after I put in a bigger drive. I’ve been fighting with Apple’s IMAP server for the last day trying to get it to let me log in, even though I have mail enabled for my account. It would be easier to just use a normal IMAP server.
Update: I wasn’t able to install Mandrake Linux. It doesn’t appear compatible with my KVM switch. I now think a better solution would be “normal” Mac OS X with a third-party IMAP server and standard administrative tools such as Webmin