Morten,
While I would suggest that you post this to the Exchange Server Admin
NewsGroup I will gladly offer my assistance. Unfortunately each e-mail
address used - whether internal or external - must be unique. So, if you
wanted to create a contact for Joe Blow and you wanted to use
(e-mail address removed) as the e-mail address you could do this. That
should be clear. However, if you then wanted to create a contact for Jane
Blow and use that same e-mail address you would get an error message.
BTW - what are you trying to accomplish? There is usually more than one way
to skin a cat!
HTH,
Cary