I have a situation where there are two organizations that are going to merge into a yet to be third over time.  One organization is running Windows 2008 with a 2003 Exchange. The other organization is running Windows 2008 with Exchange 2007.  The organization we want to merge them into to will be running Windows 2012 and Exchange 2013. The merging of operations will take place over a considerable length of time and during that period we will need to keep the two 'to be merged' entities functioning as they were while moving/blending departments/users from each to the third entity.   Until we are done we want all the users in the organizations being merged to communicate with each other as if they were in the same organization - as if they had one Exchange.  For external entities we want them to still communicate with the individual organizations being merged as if they were communicating with them directly but in fact we want to filter all email through the new system - Exchange 2013 - we just want it to look like it's coming from the original organizations.  Would Federation Services make this possible? If so I would appreciate anybody who's had a similar experience to give me the benefit of their experience and/or point me to relevant documentation for this kind of scenario.

Hi

Exchange federation would allow your organisations to share free/busy information and look up contact details, it doesn't give you any kind of merging between the organisations from an external point of view.  You also don't get a shared global address book so users need to know the SMTP address of the person in the other trusted organisation in order to look up their free/busy information.

By adding all of the current domains to your new Exchange 2013 setup and setting those domains as reply addresses, the users will still be able to send as their original organisations.  The only slight problem here is if you use a system other than Exchange to add message footers or disclaimers - that will need to be modified to add the correct details for each organisation.

Steve  

Hi

Exchange federation would allow your organisations to share free/busy information and look up contact details, it doesn't give you any kind of merging between the organisations from an external point of view.  You also don't get a shared global address book so users need to know the SMTP address of the person in the other trusted organisation in order to look up their free/busy information.

By adding all of the current domains to your new Exchange 2013 setup and setting those domains as reply addresses, the users will still be able to send as their original organisations.  The only slight problem here is if you use a system other than Exchange to add message footers or disclaimers - that will need to be modified to add the correct details for each organisation.

Steve  

• Proposed as answer by Simon_WuMicrosoft contingent staff, Moderator Thursday, November 14, 2013 10:16 AM
• Marked as answer by Simon_WuMicrosoft contingent staff, Moderator Sunday, November 24, 2013 3:50 PM

Thanks for this information.

Do you have any links to how I might "add all of the current domains to your new Exchange 2013 setup and setting those domains as reply addresses, the users will still be able to send as their original organisations."

Hi

These should help:

http://technet.microsoft.com/en-us/library/bb124423(v=exchg.150).aspx

http://technet.microsoft.com/en-us/library/aa996314(v=exchg.150).aspx

Steve