info.mailtraq.com > SMTP Services > Unresolvable HELO Unresolvable HELOThe HELO parameter should relate to the domain the email is being sent from. If Mailtraq cannot resolve the HELO paramater the message is probably a forgery, and may be rejected.
This setting is configured on the SMTP Service, Blacklists tab.
 From the Mailtraq Console, choose Options, Services, then the SMTP service, click Properties, and the Blacklists tab
Click the 'Explict Blacklists' button, then the HELO Hosts tab.
Check the 'Reject remote clients... with unresolvable HELO arguments' checkbox. | 
