In the last days I have reinstalled a mail server on a new virtual host and upgraded from debian etch to Lenny. The initial set was done by a friend of mine following this instructions. With the upgrade to Lenny however a few adjustments were required. So I describe the new setup here.
JSF is converting all date/datetime types into GMT base for rendering. This can cause a date offset of n-hours to be shown depending on the timezone you are in. You have 2 choices to deal with it:
Either you implement an application wide (global) date converter as described here or you add the timezone attribute to each of the convertDateTime tags.