Alias domain "Same mailbox.." auto-created mail alias opens mail server to backscatter

When creating an alias domain Virtualmin will auto-create an alias for "All mailboxes" with a destination of "Same mailbox in domain ".

This allows spammers to send email to non-existent accounts on the alias domain. Postfix will try to send that email to alias of domain which fails and results in a bounce ie. backscatter (and also listed on spam lists such as backscatterer.org).

A more direct 1 to 1 alias is required where the alias domain mirrors the exact aliases of the alias of domain in order to prevent this.

Thanks

Status: 
Closed (fixed)

Comments

For alias domains, Virtualmin has a feature to create 1 to 1 aliases to avoid exactly this problem ... but it isn't on by default :-(

You can enable this for new domains at System Settings -> Server Templates -> Default Settings -> Mail for domain -> Mail alias mode for alias domains , by selecting "Copy aliases from target". For existing domains, this can be enabled at Server Configuration -> Email Settings.

Future Virtualmin releases will enable this feature by default.

Automatically closed -- issue fixed for 2 weeks with no activity.