It can be anything! An apex, subdomain, or even a URL.

Results forout.securemail.name

Resolver

Location

MX

Name	TTL	Value
out.securemail.name	86400	100 local-101-101.securemail.name
out.securemail.name	86400	100 outgoing-01.securemail.name
out.securemail.name	86400	100 outgoing-02.securemail.name
out.securemail.name	86400	100 outgoing-relay.securemail.name
out.securemail.name	86400	100 trkg.securemail.name