I notice that in Outlook 2007/Exchange 2007 combo there is an option within Outlook to send OOO messages to either Internal users or Internal and External. Does anyone know what Exchange/Outlook uses to class a domain as internal or external? I have read that if it's in the AD forest, but that doesn't make sense? Also, within Exchange 2007, there is the option to send OOO (or not send) to Remote Domains - does that class them as internal or external?

Internal is from anyone inside the Exchange org, and can also include personal contacts. External is everyone else. OOTO is always sent internally - the Remote domains setting controls whether you allow them outside of your org, or not. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Thanks Simon. So let's say I have just added an internal Accepted domain of extradomain.com and assigned this manually to 20 users (i.e. given 20 of my users addresses at extradomain.com). I don't need to add extradomain.com as a Remote Domain too so that those users can send/recvd OOO messages?

Hi, > I don't need to add extradomain.com as a Remote Domain too so that those users can send/recvd OOO messages? They can receive OOF because their cantacts are existed in the Organization. Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.