The $M macro defines the hostname to use as the default domain for the mail system. This domain is appended to the From: address of any locally-generated mail. By default, the $M macro is undefined, so Unoverica Message Transport uses the fully-qualified hostname of the local system. To change this behavior you must define the $M macro to contain the domain name that you wish to use.

If you wish to use your current DNS domain name, then you may wish to reference it by calling the $m macro which contains the fully-qualified name of this host, minus the hostname (or everything after the first "."), and is automatically built when Unoverica Message Transport loads.

If you wish to use a different domain, then you will need to define it explicitly.

For instructions on configuring Unoverica Message Transport to process mail for an entire domain, refer to section 4.2 Routing Mail for a Domain.