Hexamail Guard then needs to know which email are incoming and which are outgoing (as it can process both inbound and outbound email traffic).
It does this using a set of domains that are considered 'internal', i.e. your domains.
You may only have one domain, e.g. @example.com, or you may have multiple, e.g. @mail.example.com, @us.example.com, AND @example.com.
Then setup the list of administrators who require notifications and alerts.
Welcome to Hexamail Guard
The domain list is used by Hexamail Guard to work out which email are incoming and which are outgoing. Email to recipients with addresses matching these domains are considered as incoming, and will be sent to the configured Existing Email Server. Email to recipients with addresses not matching these domains will be sent to the configured Smart Host or directly to the external email server using MX Lookup delivery.
The primary domain is used for auto-completion of email addresses and reporting to clients the name of the SMTP server. It should be configured to be one of your served domains