Mac Outlook Express 5.x Error -3211

"Domain name servers not responding"

1. Quit Outlook Express
2. Check TCP/IP settings (Apple > Control Panels > TCP/IP) making sure to add the relevant domain name
3. Dump Mac HD > System Folder > MacTCP DNR
4. Reboot and try to send & receive mail again

If the above doesn't work, a temporary resolution may be to specify the mail server setting in Outlook Express as the IP address of the mail server, rather than the mail server name.  For example, mail.tesco.net could be replaced with 212.250.162.6 (correct on 06/12/04).