ActiveSync: All Email are encrypted

[Jan Welker]

Dear Kolab Users,


I have the following problem. I am using Kolab 3 with Activesync. I 
installed it according to this 
(http://kolab.org/blog/tobru/2013/03/19/kolab-3-and-activesync) manual. 
I can connect to to it with my Android phone and everything works fine: 
Calendar, Contacts, Mail

But if I try to open a mail I see the following message:
[Unable to decrypt this message]

I am not using any thing like smime or so. And I can read them just 
fine in the web interface or over IMAP.

Any ideas?

Thanks,
Jan