From HEXONET Wiki
xDNS (extended DNS) - X-SMTP (Email-Forwarding)
X-SMTP Records
X-SMTP records have the following syntax:
www.domain.com. 3600 IN X-SMTP (local)@MAILFORWARD <target-email-address>
PLEASE NOTE: The secluding dot after the domain name (www.domain.com.) is required in any case!
X-SMTP Examples
mydomain.com. 3600 IN X-SMTP name@MAILFORWARD [email protected]
Result: Emails sent to [email protected] will be forwarded to [email protected].
mydomain.com. 3600 IN X-SMTP @MAILFORWARD [email protected]
Result: Emails sent to any address *@mydomain.com (e.g. [email protected] or [email protected]) will be forwarded to [email protected] ("Catchall").
abuse.mydomain.com. 3600 IN X-SMTP name@MAILFORWARD [email protected]
Result: Emails sent to [email protected] will be forwarded to [email protected].