Re: Bug#65256: devscripts: master.procmail example has no loop checking

[Santiago Vila <sanvila@unex.es>]

On Thu, 7 Dec 2000, Julian Gilbey wrote:

> I would like some help fixing this bug, please.  I have never used
> procmail myself, but have inherited these filters in the devscripts
> package.  There is a problem of mail loops, but I don't know how to
> fix it.  Attached is the bug report and the current filter.  Any help
> appreciated!
>
> Bug report:
>
>   The procmailrc file /usr/doc/devscripts/examples/master.procmail.gz,
>   original version of which I presume is ~edward/.procmailrc on
>   master.debian.org, has no loop checking at all.
>
>   This normally wouldn't be an important problem if a mail error message (i.e.
>   a bounce) with such a thing didn't cause Exim on the machine to go bezerk,
>   enter a mail loop, and cause a load of 100 on the poor machine! And it
>   already happened two times (or more, I'm not sure).
>
>   Perhaps Exim should have been set up to handle such things more gracefully,
>   but the script is still guilty for causing it. An addition to the script
>   that would cause messages with X-Loop header and sent from a mailer daemon
>   (Errors-To: header?) to be immediately saved to a local mailbox would, I
>   guess, be enough to fix this.

You may take the following recipe from procmailex(5) as an example:

              :0 h c
              * !^FROM_DAEMON
              * !^X-Loop: your@own.mail.address
              | (formail -r -I"Precedence: junk" \
                  -A"X-Loop: your@own.mail.address" ; \
                 echo "Mail received.") | $SENDMAIL -t

This avoids messages matching ^FROM_DAEMON but also messages
containing a special X-Loop: header: which is added to every
mail just before being forwarded.