Helo command rejected: need fully-qualified hostname

MailSite 4,5 and 6 uses the computer name as the EHLO/HELO host when delivering. You may see delivery failures reporting:

Delivery failed error message from remote server: Helo command rejected: need fully-qualified hostname.

If you receive the above message, follow the steps below to resolve the issue:

1. Get the properties for My Computer, next click the tab; Network Identification.
2. Click the properties button
3. Under Computer name specify the HOST / Computer (example; mail)
4. Next click the More button
5. Where it says, "Primary DNS suffix of this computer; enter your primary domain name.
6. Click OK and OK again

Now full computer name is: mail.domain.com

** You may have to restart the system**

If running MailSite 7 or later, then please review KB 10367 (see related items).