you can get more information with running this:
logrotate -d -f /etc/logrotate.conf
The issue I think is that
/etc/logrotate.d/zimbra
has a syntax error. Two lines are actually one:
under freshclam.log entry:
notifempty create 0660 zimbra zimbra
should be
notifempty
create 0660 zimbra zimbra
I had your error as well and modified
/etc/logrotate.d/zimbra
and
/opt/zimbra/conf/zmlogrotate
to correct the syntax error.
This seems to be something shown in
Bug 39938 freshclam logs not being rotated on linux
good luck.
John