Symptom
Users in certain domains do not receive mail sent via your server.
Solution
Affected versions of Mac OS X Server cannot relay mail to SMTP servers that have an SMTP greeting message that is longer than 128 characters. Update to Mac OS X Server version 10.1.4 or later. You may get software updates from Apple Software Downloads (
http://www.apple.com/swupdates/), or by using the Automatic Software Update feature of System Preferences. For more information on this feature, see technical document 106704, "
Mac OS X: How to Update Your Software".