You should edit /etc/exim4/exim.conf
#CLAMD = yes CLAMD = no
edit /usr/local/vesta/conf/vesta.conf and comment / remove clamav
#ANTIVIRUS_SYSTEM='clamav' ANTIVIRUS_SYSTEM=''
than disable and stop the service
systemctl disable clamd systemctl stop clamd systemctl restart exim
Test exim (send and receive email)
watch your log