Clear exim queue

The queue can be viewed with mailq, which is the same as exim -bp.
You can view individual messages using exim -Mvc <message-id>. Once you’re done, run

exim -bp | grep -Eo "[[:alnum:]]{6}-[[:alnum:]]{6}-[[:alnum:]]{2}" | xargs exim -Mrm

logrotate complains about insecure parent directory permissions

I’ve received this message recently:

error: skipping "/var/log/exim/mainlog" because parent directory has insecure permissions (It's world writable or writable by group which is not "root") Set "su" directive in config file to tell logrotate which user/group should be used for rotation.

…and a few other of similar nature. Turns out /var/log/exim/ were indeed group-writable. Easy to fix.