Danke, eben nochmal ausprobiert, das war die Lösung:

Zitat Zitat von mephisto_4711 Beitrag anzeigen
...
Search for the desired contact in your Outlook Contacts.
Double-click the contact's email address.
Alternatively, click on the desired email address with the right mouse button and select Outlook Properties... from the menu.
Make sure either Let Outlook decide the best sending format ...
Forum rockt mal wieder.