[Exim] sasl auth - exchange server as client

Hello,

we have several customers using an M$ exchange server. Their exchange
server behaves as a normal MUA when connecting to our Exim.

It seems that the exchange server tries a AUTH LOGIN. The authentification
fails at the moment. The configuration working for Outlook doesn't work for
Exchange. I tried the following two server_prompts:

Username:
Password:

User Name
Password

Both didn't work. Is there a special server_prompts value for Exchange
known? Has anyone already a working authenticator configuration for the M$
Exchange?

Thanks a lot for any help.

Michael Eichner
exim@???