How Fetchmail made me a spammer
Dag-Erling Smørgrav
des at des.no
Thu Jan 14 12:07:41 UTC 2010
Benjamin Lutz <mail at maxlor.com> writes:
> 2) Fetchmail downloads that 20MB email from the public POP3 server.
> 3) Fetchmail tries to pass the email to the local postfix server.
> 4) Postfix refuses the email with a permanent 552 error because
> it's larger than 10MB.
> 5) Fetchmail generates and sends a rejection notice, but does not
> delete the 20MB Email from the POP3 server because the
> "softbounce" option is still the default.
> 6) Fetchmail sleeps 60 seconds.
> 7) Continue at step 2).
> [...]
> - Fetchmail's defaults are dangerous. The softbounce option, which is the
> default (the manpage claims it'll be disabled by default with the next
> version,) can generate large amounts of spam.
None of this would have happened if you were using IMAP instead of POP.
Unlike POP, IMAP a) provides a way to mark a message as "processed"
without deleting it and b) does not renumber messages or reuse message
numbers.
DES
--
Dag-Erling Smørgrav - des at des.no
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