Hello all interested.
I grew awry of deleting these emails so I looked into it today.
VOTDEV suggestions are valid.
In my case I had to remove:
rm -f /etc/logrotate.d/clamav-freshclam
rm -f /etc/logrotate.d/clamav-daemon.ucf-old
So in conclusion and once and for all the output of the following command should show only one result:
root@openmediavault:~# grep -r "/var/log/clamav/clamav.log" /etc/logrotate.d//etc/logrotate.d/clamav-daemon:/var/log/clamav/clamav.log {
... preferably the "/etc/logrotate.d/clamav-daemon" file, others, delete them without second thoughts 
Hopping someone will find this useful, I say: Farewell!