Hi I have 2 Exchange servers 2003 and 2007 in two different AD and distint organization ( @domain1 and @domain2). My question is, can I have a list of joint distribution, i.e. an address list that contains all the addresses of both domains. Thanks

Sure. Since these are 2 sep orgs, then each has its own GAL yes? If you wanted a DL with members in each org, create mail-enabled contacts for the external contacts using the SMTP addresses of the other org for each. Create the DL, add the internal users and mail-enabled contacts that represent the external users to the DL. Ensure hat each DL allows authenticated users to send to it. Do the same thing in the other org, this time the mail-enabled contacts represent the first orgs users and their SMTP addresses. Make sense?

Comments that both domains Exchange and Windows are completely different, there is only trust relationship. A server is Ex2003 and the other Ex2007