Entourage timing out on Airport Network

Help! I have had an iMac for the last year and today purchased a MacBook. I have successfully networked them using Airport, and have gotten the MacBook connected to the internet via the network. (The iMac is on an ethernet DSL connection.) I set up my Entourage account and when I try to send/receive, it keeps timing out. I have double checked all the settings and the error message says "An operation on the server timed out. The server may be down, overloaded, or there may be too much net traffic." Error-3259.
Any ideas? I appreciate any help out there - thank you!!

In my Exchange/Entourage setup, I've gotten this error when I didn't have the SSL-connection checkbox checked. ("This DAV service requires a secure connection")

It could also be a firewall issue, I suppose. Are you using Internet Conection sharing on the iMac? If so, what happens when you turn off the iMac's firewall?

Thank You - concerned about firewall?

Thank you - turning off the firewall worked - absolutely awesome! But, how concerned should I be that the firewall on the iMac is off? Everything I've heard is 'absolutely don't turn off your firewall...'
Again- thank you for the help!!
Sincerely,
Holly Bryant :mac:

No, you're right...but now we know that the firewall was causing the problem.

What you need to do now is create firewall rules (in the Firewall tab on the iMac...click the New button) to open only those port numbers that Entourage is using to handle your mail. You can then turn the firewall back on.

Exactly which ports those are depends on how you get your mail. POP3 needs port 110, IMAP might need port 143, 220, or 993 (when used with SSL.) Exchange might need 80 or 443. SMTP (for sending mail) might use port 25, or something else. (There's a list here.) You'll probably have to experiment to determine which ports are necessary; your account settings might give you a clue.

It all works like a dream now!

I can't tell you how much I appreciate the help. I'm so glad I found Mac-Forums because this is the first time I've gotten a worthwhile answer on a forum! I enabled ports 110 & 25 and turned the firewall back on and Entourage (and me!) are still happy!!!! Thank you sincerely for your help! I'm going to keep watching the forum for tips & tricks.
Best Regards,
Holly