[bci]

Thanks for the tips!
Interactively running zypper will clear this, of course (the latter idea is too dangerous for us as also kernel updates would then be done silently).

The question remaining is if it is correct behaviour for postfix to treat a file with just one non-printable character as a PCX attachment, rather than sending it as-is...
But this may better be posted in the Applications forum, I guess.

Thanks and "closed".