I'm getting the following error from my Ubuntu server: exim paniclog /var/log/exim4/paniclog on (my server FQDN) has non-zero size, mail system might be broken. I found a solution on the web here. Basically, I just need erase the paniclog by entering the following code: sudo rm /var/log/exim4/paniclog So, I know how to get rid of the error, but I don't know how it started, and how to not let it happen again. Any explanation? Thanks in advance.