Non-delivery of email sent by automated services to altlinux.org

Quite often automated user verification emails (from other wikis, forums, services, etc.) don't pass through to my altlinux mailbox (@altlinux.org). One such case has been investigated and the reason was:

altlinux.org appears to be doing sender-callback-verification... the apache@mozilla.org address indeed appears to be missing now. It used to exist (exactly for this reason) so I'm not sure what happened to it. I just put it back.

For administrators of external services that send automated emails:

If the users from altlinux.org have problems with receiving the messages, please make your service even better: make sure your service has everything to pass this "sender-callback-verification"!

Suspected similar cases of non-delivery and related discussions

Bad (not fixed)

• https://bugs.freedesktop.org/show_bug.cgi?id=73703 (a Bugzilla installation)
• ? https://en.bitcoin.it and https://ru.bitcoin.it (a MediaWiki installation)

General solution

• https://bugzilla.wikimedia.org/show_bug.cgi?id=21347 (in MediaWiki)

Good (fixed)

• https://bugzilla.mozilla.org/show_bug.cgi?id=524822 (a MediaWiki installation)
• https://bugzilla.mozilla.org/show_bug.cgi?id=153051#c5 (a Bugzilla installation)
• repo.or.cz's key updates