On Sun, 2026-05-03 at 20:20 +0000, Andy Smith wrote: > Although I confess I don't really understand why a > process launched by monit would be directly trying to write to the > postfix directory as I would have thought it talks to postfix and > then something from postfix delivers the mail. But since the same > thing appears to have happened with netdata and other software then I > think it's got a good chance.
Typically such applications use /usr/sbin/sendmail to send mail, which is usually a binary supplied by the MTA you use (Postfix in this case). Depending on the implementation & configuration of /usr/sbin/sendmail it might try to do anything from dropping a file in a specific location to connecting to an external mail server. The problem might indeed be systemd or AppArmor or similar blocking sendmail from doing its thing (possibly also because it’s being run with restrictions set for Monit, which don’t take into account the specifics of the /usr/sbin/sendmail you are using). -- Jan Claeys (please don't CC me when replying to the list)
