Horváth Zsolt authored Oct 12, 2022 and Matthias Andree committed Oct 12, 2022

I have a misconfigured MTA server to which I transfer mail from an IMAP
account using fetchmail. Although I use the --softbounce switch,
fetchmail still deletes the email even in case of unsuccessful delivery.

The problem is caused by the fact, that the close_sink() call returns
with the value TRUE not only in case of successful delivery, but also in
case of a permanent (code 5xx) error. Then the fetch_messages()
procedure will no longer know, whether the message can be deleted or
not, because it does not have the information that the close_sink() call
returned TRUE because the delivery was successful or because it is
expected that the delivery will not be successful later either, so the
value of the softbounce switch cannot be taken into account at this
point.

Solution that in the case of a permanent error, the close_sink() call
does not return a fixed TRUE value, but the negated value of the
softbounce switch.