After comparing different options (NAS, Amazon S3) I decided to go with the Amazon S3 Web service.
The Webserver Apache is successful updated to version 2.2.9. There are several security enhancements and bugfixes in this version.
The Antivirus Scanner for the Mailserver is now updated successful to version 0.93.1. This version contains improvements for scanning HTML and PDF files and various other bug fixes.
Courier Authlib was just updated successful to version 0.60.6.
The certificate for the webserver is renewed. Now it is valid till the 26th of May 2009.