Extend POSTFIX_LOCAL_REGEX to include mail received from localhost

[whitequark]

This matches e.g.:

Received: from mail.whitequark.org (localhost [IPv6:::1])
    by mail.whitequark.org (Postfix) with ESMTP id CDCA2E08B7
    for <whitequark@whitequark.org>; Thu, 02 Oct 2025 06:12:47 +0000 (UTC)

Thanks for the nice extension!

[williamdes]

Can you check the tests, it breaks them

[whitequark]

Fixed. I also took the opportunity to add IPv4 and IPv6 tests for the new functionality.

[GermanCoding]

Thanks!

[whitequark]

Thank you! Is this worth releasing a new version?

[GermanCoding]

Yeah definitely at some point. I like to batch a few changes together if it's not urgent, e.g. we also have some localisation fixes in the pipeline that may go in the next release, so I'm holding off on releasing right away. You can install the dev-master version on composer if you want this now.

[whitequark]

I actually use Nix rather than Composer so this isn't a blocker for me in any way, I just prefer to keep sources organized.