Paniclog has non-zero size, mail system might be broken

If you get this message, after the installation of Exim4 :

ALERT: exim paniclog /var/log/exim4/paniclog has non-zero size, mail system might be broken

Try these commands :

apt-get autoremove

Or

sudo apt-get remove --auto-remove sendmail

There is an incompatibility between sendmail and Exim4 as they use the same port (port 25).

Then :

sudo service apache2 restart
/etc/init.d/exim4 restart

If you still get it :

nano /var/log/exim4/paniclog

Remove all the lines. Ctrl+O, Ctrl+X.

/etc/init.d/exim4 restart