Stopped MTA service but mail flow is still working

Products

• Messaging Gateway

Issue/Introduction

The MTA service has stopped and cannot be initiated.
Despite this, the mail flow remains unaffected, and all emails are being processed correctly.

Resolution

In the SMG web interface follow the path:
[Spam → Settings → Sender Authentication → Domain Authentication]

Within the interface, there are three radio buttons alongside a list for domain authentication.
It is necessary to note that choosing the option to authenticate all domains still requires the inclusion of at least one domain in the list.

Please add a domain to the list. 

After adding a domain to the list, restart the Mail Transfer Agent (MTA) service.
You can do it from the Web interface following the path: [Administration → Hosts → Configuration → hostname], or using the below command:

service mta restart