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Eprs_AdminFlag for Austria

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Cross Forrest Mailbox migration

Hi Experts,

we have a project to do with migrating mailboxes from EXCH-A to EXCH-B.
Both exchange servers belong to different forrests.

Do you have a manual or link for that ?

The EXCH-A is version 2016
The EXCH-B is version 2013.
Is this possible ?
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It will be easy to use 3rd party softwares and migrate from forest A Exchange to Forest B exchange.

Can you explain what your client's requirement?
Maybe we can propose something better.
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We will have to migrate thr mailboxes from forest A to forest B.
The users still in forest A but the mailbox is in forest B.

Can we use new-migrationbatch for that ?
Because the mailbox in the source is on EX2016 and the traget exchange is EX2013.

What do you think ?
You need to have two way trust between forests and add the Target Exchange organization .
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Saif Shaikh
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Taking out PST also take out the X500 address of mailboxes and add them back in the new mailboxes on migrated forest..
You're going to have to upgrade your 2013 server to 2016.  Unless you want to test your upper limit of frustration don't try to migrate using .pst files.  Since the mailboxes all live in a separate forest there is no need for legacyExchangeDn / X500 addresses either.  The challenge you'll face is password and SID history both of which are accounted for in the ADMT (Active Directory Migration Tool); however, it's not really appropriate in this instance since the AD users and mailboxes are already established in the target.  If flipping the migration from 2013 to 2016 isn't an option you'll most likely want to shell out the $9.99 per mailbox for Migration Wiz, otherwise the next best option I can think of is introducing a third forest (similar to a resource forest) to facilitate the unique position you're in.  I'm happy to help if you need a hand.
Hi Jason,

can you confirm, I have to upgrade the EX2013 ?

Now when I try to move the mailboxes to the new forrest with GUI, I get this error:


Any ideas ?
what does it mean ?

do I need to trust some certificates ??
Have you tried below command:

New-moverequest -identity "" -BadItemLimit 100 -AcceptLargeDataLoss

Modify the baditemlimit as per your needs.
Hi Saif,

it hasnt to do with the dataloss or baditemlimits.
I get SSL errors.
Provide the complete error information. Incomplete information will not lead to solution.

You can remove or colour the sensitive information in the error liek domain name and all.
I hope I can get this info nect week
Here is the full error:
1. Have you tried moving one or two mailboxes by themselves?

Can you move a single small mailbox over?

If yes, it may be a matter of mailbox size and this post may help:

2. Try modifying MSExchangeMailboxReplication.exe.config on the target CA server as follows:-

              binding name="MrsProxyClientBinding"
          <reliableSession ordered="true" />
            <readerQuotas maxArrayLength="3048576"
                          maxStringContentLength="3048576" />
          <httpsTransport authenticationScheme="Negotiate"
                          allowCookies="true" />
I have tested several different mailboxes, always same error.

ok I will check next week.
Hi All,

I have upgraded now to Exchange version 2016.
Now on both sides I have version 2016.

What kind of config is needed to migrate from Forest A to Forest B ?
Thanks Saif,

after the exchange Upgrade to 2016 on site A, I was able to migrate all mailboxes.
You are most welcome...Glad to hear your issue was resolved.