This is just a guess but from the sounds of your description, appears that
the postal code is being saved as a numeric value and whatever you have in
the PLZ field is considered invalid or non-existant. Unless I'm mistaken -
the postal code is generally written as <##### City > within a German
address. What specific value is in the postal code field itself when looking
at it within Outlook (not as a complete address but the detail view of the
address) - is it just the 5 digit number? Is there any value in there at all
or has the postal code actually been entered with the name of the city?

If there is a value in the postal code field itself, you may want to try is
exporting the file as a CSV file and then opening that with Excel and see if
that makes a difference in terms of how Excel is picking up the data.

Another possible element that can add to how things are handled could be
based on what your computer's regional settings are set to on your system as
we're discovering from our European customers where MS Office language used
and regional settings do not always match.

Karl

__________________________________________
Karl Timmermans - The Claxton Group
ContactGenie - Importer 1.3 / DataPorter 2.0
"Power contact importers for MS Outlook '2000/2003"
http://www.contactgenie.com