I have a senario and do not know if there is a solution or not. Here at Company A we use Exchange 2003 on our Domain. Our internal application systems automatically send emails via our exchange server to clients via group mailboxes. Company B are looking to partner with us and use our applications. They also have their own seperate Exchange 2003 system on their own domain. In using our applications we need to set up users with their own mailboxes on our Exchange server. They will connect via Terminal Services and run our applications and mail within the session. We will associate our exchange mailbox for the users of Company B to a reply address of their companies email address. Ideally we want them to be looking at one shared outlook mailbox and not two seperate ones. I can do this by forwarding all mail from one mailbox to the other and visa versa, but it is messy and takes a lot of admin. Q. Is it possible to have certain mailboxes from Company B's exchange server to Syncronise with their mailbox account on our Exchange Server. They will be connected to our WAN via a 10MB circuit. Also if there is a solution does anyone know what the bandwidth is per mailbox syncronisation.