Hello technet, To give some background before i ask my question: The network is currently configured such that we have a parent domain, and several child domains for each location. Some of the locations have their own domains, that do not belong to the parent. They however receive services from the from main domain, such as e-mail services, etc. Our Exchange solution is a centralized solution, which sits at the parent domain level. Based on the above, some of the locations with their own domain do have to use 2 different log-ins. One for their domain, and one for E-mail/Outlook. A customer has requested to know what would be required for them to be able to have a single sign-on. They have their own domain, but receive e-mail services from the domain they are not a part of.

Only with a trust. If you don't have a trust then you can't really do anything natively. There might be third party applications that can do something for you, but you would still have to maintain two sets of usernames/passwords. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Agree there's no native way since it's a completely separate security boundary. I'm not aware of any third party apps.James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com