On Tue, 30 Nov 2021, Marc Shapiro via Dng wrote:

>I am getting e-mails like the one below all the time, now. I had this problem
>once before and I think that all I had to do was clear the paniclog with '>
>paniclog', but that does not seem to be working, now. I cleared it this
>morning, and when I just checked it was filling up again. It looks like I get
>three lines every half hour. This is preventing me from receiving e-mails sent
>by a cron job that runs a backup script. Any ideas on how to get rid of this
>and not have it come back would be greatly appreciated.
>
>Marc

Make sure your exim configuration matches with the version of exim you have
installed. Make sure there is no .dpkg-new laying around in /etc/exim4. Check /usr/share/doc/exim4-base/changelog.gz.

Notably, in /usr/share/doc/exim4-base/README.UPDATING.gz:

# Exim version 4.94
# -----------------
#
# Some Transports now refuse to use tainted data in constructing their delivery
# location; this WILL BREAK configurations which are not updated accordingly.
# In particular: any Transport use of $local_part which has been relying upon
# check_local_user far away in the Router to make it safe, should be updated to
# replace $local_part with $local_part_data.

Cheers,
                 Ludovic