acknowledge alerts with email (postfix)

list Frank Schmerler
Fri, 20 May 2011 17:17:17 +0200
Message-Id: <user-3078c273b146@xymon.invalid>

Hi

I've installed Xymon 4.3.3 on Centos 5.6 with postfix. Everything is working fine but I can't acknowledge alerts with email. 
I see the email is coming to the default location from postfix (/var/mail/xymon) and nothing happened...

Is there a howto or has anyone an idea how to configure this ?

Thanks
Best regards

Frank