If you use a mail-server with very low ram (< 500 MB) and a slow CPU then it might be necessary to disable the antivirus filter functions in ISPConfig 3 as amavisd and clamav might be too heavy for your server hardware.
Here are the steps to disable clamav:
/etc/amavis/conf.d/50-user end comment the following two lines
@bypass_virus_checks_maps = ( \%bypass_virus_checks, \@bypass_virus_checks_acl, \$bypass_virus_checks_re);
it should look like this:
# @bypass_virus_checks_maps = ( # \%bypass_virus_checks, \@bypass_virus_checks_acl, \$bypass_virus_checks_re); @bypass_spam_checks_maps = ( \%bypass_spam_checks, \@bypass_spam_checks_acl, \$bypass_spam_checks_re);
Notice that I didn’t disable SPAM check, disabling clamav was enough for me.
2. Restart amavis
service amavis restart
3. Stop clamav and freshclam
service clamav-daemon stop service clamav-freshclam stop
4. Disable clamav and freshclam from running on boot:
update-rc.d -f clamav-daemon remove update-rc.d -f clamav-freshclam remove