The cause of the problem may be in pidfile ... in your previous mail you
compared the contents of /var/run/clamav/clamav-milter.pid.fixed file
with the running process:
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# cat /var/run/clamav/clamav-milter.pid.fixed
12781
# ps -ef | grep clamav-milter
clamilt 12781 1 0 16:19 ? 00:00:00 /usr/sbin/clamav-milter
--quiet --external --dont-wait --force-scan --dont-log-clean
--server=localhost --pidfile=/var/run/clamav/clamav-milter.pid
local:/var/run/clamav/clamav-milter.sock
--8<--
however, monit was configured to check the pid which is stored in
/var/run/clamav/clamav-milter.pid (containg the incompatible format):
--8<--
Process Name = clamav-milter
Group = milter
Pid file = /var/run/clamav/clamav-milter.pid
...
--8<--