Unable to resolve dependencies on update

[Timotheus Pokorra]

>> It seems like wallace finally arrived with the latest update. However, 
>> when trying to update, ich get this. Please advise. Thank you
> 
> Same for me, i'm on centos 6.4.

No idea where this version pykolab-0.6.9-13.9.el6.kolab_3.1 came from. 
Probably something was in a strange state over the weekend.
On IRC, this solution was posted:

yum downgrade pykolab kolab-cli kolab-saslauthd kolab-server 
postfix-kolab
yum update