I run a Postfix server that hosts a small, alias-based mailing list. Let's say
people@myserver forwards to
alice@someprovider might use a more restrictive spam filter than I do.
When a spam mail from (forged)
people@myserver arrives, and my spam filter detects it as spam, it is rejected in the SMTP phase --> no harm done.
However, when the same mail gets through my server, my server tries to forward it to alice, and her server rejects it during the SMTP phase, my server creates a bounce message to the innocent backscatter victim. (Which makes sense from the point of view of my server, but it's annoying for the backscatter victim.)
Is there a way to prevent this behavior? I don't want to turn off NDRs, since (in general) they serve a legitimate purpose.