IMAP on Apples

We have been having some unusual problems with the IMAP servers while using Apples. We have a G5 (OS X) using Apple Mail, an iMac desktop (OS 9) and an iMac laptop (OS 9) both using Outlook.

The connection to the IMAP server seems spurious.

At times G5 or the desktop will not send mail. It says it cannot recognize the mail server. The laptop seems pretty reliable. The settings are the same on each machine.

Is it possible to have all three machines access the same account on the same mail server at the same time? Or should only one be connected?

Do you know of any problems with IMAP servers and wireless routers?

Another unusual thing is that sometimes the G5 will not recognize the Webmail site. I don't understand why this is. I can reliably access the webmail site from my PCs on the same network.

I have no problems using the IMAP server from either of my Macs (a G4 minitower & a PowerBook G4, both running OSX 10.3). I only use the IMAP server to receive mail; I send mail using my ISP's SMTP server, since they block port 25.