If you have an email with multiple levels of subparts, and you call body_str_set() or any other modifier on a deep part, the top level Email::MIME's ->as_string (and other things) should notice that it was changed and reflect those changes accordingly.
If you have an email with multiple levels of subparts, and you call body_str_set() or any other modifier on a deep part, the top level Email::MIME's ->as_string (and other things) should notice that it was changed and reflect those changes accordingly.
(See https://github.com/wolfsage/Email-Footer/pull/8/commits/5d807445e94b2ad6ef770ba40126be171d5558eb for an example of something working around this problem).