amavis in kolab3 on Centos6.4

[JP Horst]

Hi,

I have regularly emails blocked by amavis.
Maillog says e.g. :
..... (04755-04) Blocked BAD-HEADER-0 {BouncedInternal,Quarantined} .....

Nevertheless /var/spool/amavisd/quarantine is empty and most of the mails also 
don't show up in /var/spool/amavisd/tmp.

Amavisd-release xxxx does not work and complains:
450 4.5.0 Failure: Config variable $QUARANTINEDIR is empty at (eval 109) line 
306, <GEN111> line 4
And indeed this directory is not defined in amavisd.conf.

Notifications about blocked mails are not sent to anyone.

How does kolab3 handle these mails?
Where are these mails?
How do I get them delivered?

Thank you for any help,
Jens-Peter