/etc/amavisd.conf contains $log_level twice
In the /etc/amavisd.conf created by the installer, the $log_level entry is present twice: once as "$log_level = 0;" and once as "$log_level = 5;".
The entry with 5 comes last, so it overrides the first one, causing amavis to write tons of unnecessary debug info to the syslog. This is bad on a production system, so I suggest to remove the second entry completely.
(This is on openSuSE 12.2 beta2.)