Options | Outgoing Mail | SMTP Settings-tab
The SMTP settings dialog allows the configuration of additional settings for the SMTP client.
The default host name used in mail server HELO/EHLO conversations can be adjusted here.
When a mail server connects to another one to deliver mail, it 'says hello' the other server with its own name.
This should correspond to the internet name of the server.
For example: mail.mydomain.com
So a DNS lookup to mail.mydomain.com should return the IP address of your server.
Many mail servers perform this check, and if the HELO name does not correspond to your IP address, they reject your mail.
The Local Domain Name is that set in Options | Server
Specify Host Name allows you to set it yourself - mail.mydomain.com
Perform Reverse Lookup will offer as the HELO a match to the lookup by the remote server you are connecting to.
Specify Host Name
This setting is used to control the HELO parameter issued when the SMTP client is connecting to a remote server. It does not change the local domain as issued by the SMTP service (the '250' response).
This control sets the HELO value sent by Mailtraq to initiate the 'conversation' with the remote mail server. You can confirm that your setting is being used by doing a test 'send' of a message, and then observing the Mailtraq Event Log
Take care if you specify the HELO name here that it is not overridden by the SMTP security settings (the padlock icon) where you can also specify the outgoing HELO name.
Limit Recipients Per Message
This dialog allows Administrators to control how many recipients a message may have, and is normally used to control abuse.