sgfifford, that's really the heart of my question -- is it incumbent upon the module user or author to check for and work around this? I normally have little sympathy for module users -- if you are willing to accept the benefit of someone's code, you should accept the burden of playing by its rules -- but in this case, I was using MIME::Entity, which used Mail::Internet, which used Mail::Mailer -- nowhere in MIME::Entity's API was it clear that a fork would be happening.

Based upon what I've heard in this node and elsewhere due to this experience, I now beleive that CPAN modules that use fork(), open-to-pipe, or similar calls MUST account for the possibility of being called inside an eval -- or else document that the code MUST NOT be called inside an eval without checking for a fork gone wrong.

I don't believe this is especially burdensome to CPAN authors, because the patch to Mail::Mailer that solved this problem was only a few lines of code (most of which were splitting out a logic condition into an if/then/else). Am I on the wrong track here?