Exchange 2013 cross forest migration

Our current scenario is as below

domain: abc.logo
Exchange 2013:

New Exchange 2013:

We need to migrate to new and then need to decommission of current

We assume that we will need to do cross forest exchange migration by creating trust between two domain and usign ADMT tool for the users and mailbox migration.

Kindly suggest the best practises or steps or referance links.
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Will SzymkowskiSenior Solution ArchitectCommented:
So something like this is pretty envolved. High Level Steps are below...
- create forest trust to 2nd domain
- setup/configure ADMT (member server in source domain)
- migrate AD Objects to 2nd domain
- migrate mailboxes using Prepare-MoveRequest.ps1 script

You will have to use the prepare-moverequest script because the ADMT tool does not migrate Exchange attributes.

rigelnetAuthor Commented:
Is It possible to use ADMT tool for the exchange 2013 cross forest migration?

we will install new exchange and will migrate mailbox using admt tool and then enable all users in new domain.

would that works? Kindly confirm.
Miguel Angel Perez MuñozCommented:
ADMT tool is not for Exchange, is used to migrate AD user/computer accounts.

I´m currently involve on cross forest migration (from EX2010 to Ex2013) due company adquisition. I´ll will do using this steps (be same for you):

1- Setup your new forest, configure Exchange servers, destination forest must use source Exchange as smarthost to route emails to internet.
2- Create trust between both domains.
3- Install ADMT on source forest.
4- Configure Password export server (otherwise you need to create password for all users).
5- Enable Proxy MRS
6- Install certificates.
7- Create one test user, uses script prepare-moverequest.ps1. This script creates MEU on destination and a X500 email address used to route mailflow during process.
8- Use ADMT to migrate user. Disable SID filtering and export user password. After finish this step, you have moved user but not mailbox.
9-  Move mailbox, can use EMC or new-moverequest cmdlet. After this point, must to clean cache on Outlook clients or setup any kind of GAL sync between both forests.
10- Remove password requirement for this user (set pwdlastset to -1)
11- Test (inbound, outbound, access from owa...)
13- Optional: you can setup a federation trust to share free/busy from calendars between forests.
14- Move service accounts/groups using ADMT.
15- Bulk move (prepare-moverequest + admt + new-moverequest)
16- Change inbound/out mailflow from source to destination servers
17- Move computer accounts
18- Do a clean SID/remove federations, trusts...
19- Decomission old forest.

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Will SzymkowskiSenior Solution ArchitectCommented:
As i stated in my original comment the ADMT tool does not migrate mailboxes to another Forest. It only migrates the AD Objects. You need to use Prepare-MoveRequest.ps1 script to migrate mailboxes to another forest.

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