The above code is preceeded by a routine that sends cooker mailing list messages directly to the default mailbox. This is because cooker is a high volume mailing list which I don't want to feed through spamassassin.

I had posted a message to this list respecting whether it would work to have set the exitcode to 553. The fetchmail man page states that smtp return code 553 would cause fetchmail to remove the message with the server without any attempt at bouncing it.

I received no reply so I went with simply returning exitcode 0 so that fetchmail would treat the message as having been delivered.

I would have preferred the other return code in the hope that I could get the fetchmail log to leave a trail for any rejected messages. The .maillog file does not leave such a trail.