Say i am migrating a user 'Mr.A' mailbox from abc.com to xyz.com in exchange 2010 environemnt, why do i need a disabled AD object for Mr. A in xyz.com prior to migrating  ? pleas

Hi,

To move a mailbox from one Exchange forest to another, the Exchange target forest must contain a valid mail-enabled user with a specified set of Active Directory attributes.
When you run Prepare-MoveRequest.ps1 script or ILM with sample code to synchronize required attributes between source forest and target forest. After run New-MoveRequest to complete mailbox move and change AD object from mail enabled user(MEU) to MBX. More details about Cross-Forest Mailbox Moves, please refer to below blog:
http://blogs.technet.com/b/exchange/archive/2010/08/10/3410619.aspx
 
Best Regards,
Allen Wang

Hi Allen,

We could achieve this by using an enabled object ( in this case mail-enabled user ) than why specifically we use disabled object prior to migration ? I Looked at scenarios in quest migration manager for exchange and ADMT or indeed when we use a native way with no tool to migrate, in each case we gotta do this by disabled object in other domain. ? please suggest

Hi,

As above mentioned, when we run ILM and PrepareMoveRequest, it will create disabled MEU account in target forest with required attribute. Then run move request to complete migration.
We do not need to disable exist AD account in target forest.

Best Regards,
Allen Wang

Hi Adi,

Agree with Allen .

1.First step is to run the prepare-moverequest.ps1 and that will create the disabled MEU (Mail user object) in the target forest.

2.Then the second step is to use the ADMT tool to migrate the user account with SID and password.For password migration you need the PES in anyone of the domain controller on the source forest.

Note : Before doing the second step we need to execute the script on the ADMT server which is to exclude the exchange attributes during the user account migration from ADMT .Script is defined on the below mentioned link.

Reference Link :  https://social.technet.microsoft.com/Forums/office/en-US/f1f55efd-667e-415d-b936-8457ccacc8b0/cross-forest-migration-2007-to-2013

3.Third step is to move the mailbox from the source forest to target forest .

Hi Nithyanandham / Allen,

Just bit curious to know why every other migration tool such as ADMT, quest or may it be the native way we do uses a disabled MEU account  , can't we use enabled  MEU account ?

Hi ,

To be frank i am not aware of quest but i can suggest you in ADMT and also in exchange cross forest migration.

I hope you are doing the cross forest migration from exchange forest to exchange forest , so on such case by using the prepare-moverequest.ps1  we can have only have the disabled MEU on the target exchange forest until the remaining attributes of the user object was migrated from ADMT.

While running the prepare-moverequest.ps1  it will not completely move all the active directory user attributes from the source forest to the target forest but it will move all the exchange attributes to the target forest and finally it will make the MEU object in the disabled state. Since all the exchange attributes are already migrated to the target forest ,so prior to use ADMT user account migration we need to exclude the exchange attributes by running the script on the ADMT server .After doing so exchange attributes will not be migrated but the required user attributes will be migrated to make the MEU to the enabled state.

Reference Link for types of exchange migration between the forest :

http://blogs.technet.com/b/exchange/archive/2010/08/10/3410619.aspx