While migrating mailboxes from Exchange 2010 to Exchange 2013, it’s very slow.

Checked if there is any issues in Network, also gone through Firewall settings and found no issues.

But status shows Syncing



Enhanced migration procedure

In this article will show the enhanced Migration procedure.


Step1: open file


Open the file located in the drive as shown below:

“MSExchangeMailboxReplication.exe.config” file located at “C:\Program Files\Microsoft\Exchange Server\V15\Bin”





Right click on the “.config” folder and change ExportBufferSizeKB=”512″ to 10240 and restart ‘Mailbox Replication Service’, as shown below:




Rerun the Mailbox Migration and you can recheck the status.


Step2: Disabling index


Sometime disabling index might work some time so the temporary you can follow, later completion we can re-enable as shown below

To know if it’s in Enabled or disabled run the below command.

Get-MailboxDatabase -identity “DBNAME” |fl




To change the IndexEnabled to False run the below command:

Set-MailboxDatabase “DB1” -IndexEnabled:$False




Rerun the Mailbox Migration and you can recheck the status.


Step3: Change replication


Changing the Mailbox Replication Service throatlling value from regedit might also give you the best result.

Follow the steps suggested below:

Go to registry edit as shown below:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\MSExchange ResourceHealth





Modify the MRSThroattling value from 1 to 0. Then restart ‘Mailbox Replication Service’.




Post completion of migration again change value back from value 1 to 0.

Rerun the Mailbox Migration and you can recheck the status.

Ok fed up still the problem you can try using the below command using the switch as “Priority emergency”


Run the below command:

New-MoveRequest -Identity “” -TargetDatabase “DB1” -Priority emergency




Note: If you are running for multiple mailboxes need to change the above command based on your requirements.


See also

The other articles about Mailbox Migration: Mailbox Migration – Exchange 2010 to Exchange 2016