Roller Network Help - Mail Domain Aliases
Mail domain aliases allow you to create an alias domain that is functionally identical to an existing mail domain without having to create and manage individual settings as you would for a new mail domain. Aliases are a simple way to add domains that will have identical settings to an existing mail domain.
To create an alias for a mail domain, simply click on the "Add Mail Domain Alias" button. Enter the alias domain name and select the target mail domain. When a message is received for an alias domain it is rewritten into a mail domain. As such, aliases will only appear on the alias configuration page since they are only pointers to an actual mail domain.
Subdomain matching is not included in alias domains. If a mail domain is disabled, its aliases will also be disabled. Deleting a mail domain automatically removes its aliases as well.
Search Order
Mail domains are resolved in the following order: exact mail domain name match, mail domains with "include subdomains", and finally mail domain aliases. If an exact or "include subdomains" match is found those settings will override an alias.
Technical details
Let "example.net" be a mail domain alias to the mail domain "example.com". When a connecting mail server sends the SMTP command "RCPT TO:<user@example.net>" it will be transparently processed as "RCPT TO:<user@example.com>". Subsequent SMTP transactions will be performed using "RCPT TO:<user@example.com>".