how do i prevent exchange changing the to email address

[MArc]

hi,
i'm connected to a domain X.com
in that domain there is an Echange 2003 server to which i'm connected
now i want to send to (e-mail address removed)
in the domain the user John Doe is known, email : (e-mail address removed)

when i want to send to (e-mail address removed) outlook changes this address to (e-mail address removed)
but the address Doe@ is internal, not external...
in other words, the Doe@ address does not resolve at my smtp server

i do not send my email through this exchange server, but through an isp smtp
server
i'm also not logged on the the domain X.com

if i delete the exchange connection all works well
how can i prevent exchange messing with my email addresses
i tried deleting the .nk2 file without luck...

tia,
marc