I have a customer on a Mac who can't relay mail through the server. I have tried everything I know to do, including adding their ip address to exim's /etc/relayhosts file and making sure they have "Allow Authentication" checked. Any ideas? He has the same problem with both OLE 5 and Eudora.

Hi!
Just check for his IP in the /etc/hosts.deny.
It may be there and hence the problem.
Have a great day :)

regards
amar

If you can't get this resolved..you could just setup a web based email script for him...

Maybe his ISP is blocking port 25. A lot of them are doing this.

Q: Why do I get a "NO SOCKET" error when trying to send email to my email server (smtp.yourdomain.com)?
A: If you use Mindspring, Prodigy, or Earthlink for an ISP, they have installed a firewall on the SMTP port. Please visit http://www.bitserve.com/advocate/mindspring.html for more information. These companies are undoubtedly not the only ISP's out there that block SMTP access to remote servers. Please contact your ISP to see if this applies to you.

Just check for his IP in the /etc/hosts.deny.
Already thunka that. Nope. :)
If you can't get this resolved..you could just setup a web based email script for him...
He already has access to Neomail, but that can be quite a pain sometimes.
Maybe his ISP is blocking port 25. A lot of them are doing this.
From his mail header:
femail9.sdc1.sfba.home.com
Surely the cable providers haven't setup any firewalls?