Hi My domain is uk.company.com in the company.com forest. There is another forest named external.com. There is a VPN between our network and theirs. We have some users from External.com in our buildings. They have AD accounts in our AD, so they can access resources such as printers etc, but they would like to access their mailboxes hosted on their Exchange server in their forest. We would like for them to access their mailboxes from our building using MAPI, not Outlook Anywhere, since the network connection is good. The relevant ports can be opened on the VPN firewalls, DNS has been set up etc. There is currently no trust between the two domains. Users in the uk.kam.com domain were going to access their mailboxes in External by using their External.com AD account, i.e. their Outlook profile would be set to use External's Exchange server, and when prompted for authentication they would enter EXTERNAL\User1 etc. My query is...how long will this authentication last for. Presumably, the ticket that they were assigned by the DC in External they authenticated would expire at some point, would they need to enter their credentials in again to authenticate against another External DC, or would this be transparent to them?

dup posthttp://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/9ef863ac-a83c-409e-81ac-9a1cff5c525c Mike Crowley A+, Network+, Security+, MCT, MCSE, MCTS, MCITP: Enterprise Administrator / Messaging Administrator