For some reason, a running clamAV daemon (clamd) went South sometime yesterday. Since Exim relies on a clamd being present for content- scans, it was failing new messages with a temporary 4xx code. I’ve now done what I should have done to start with: integrated a check on clamd into our Nagios monitoring system. In order to check the daemon’s presence, I use clamdscan on a file which should always be there (/etc/passwd) and check for an exit code, returning that to Nagios. Status at the moment? Green. :-)