Cutover Migration Sync

Question

I have a cutover migration from an on-site Exchange 2010 server.  The initial sync was successful and the following incremental syncs worked.  However, I changed DNS to point to the 365 servers before the final sync.  I mistakenly thought syncs would continue after the DNS change.  I am missing about 1 day of email.  

The batch is still in place, but need to find out if another sync is possible.

Answer 1

Hi Jmore10,

When you start a batch, you need to only change MX record first. After that, Office 365 mailboxes were synchronized at least once after mail began being sent directly to them. To do this, make sure that the value in the Last Synced Time box for the migration batch is more recent than when mail started being routed directly to Office 365 mailboxes. When you make sure that and the batch is finished, you can delete the batch. You can change all NDS records after the steps are finished above.

Here is a reference:

Perform a cutover migration of email to Office 365

If anything is unclear, please feel free to post back.

Best Regards,

Erick

Answer 2

thanks for the information.  Since we only missed one day of sync, we are just going to deal with it.  But, again, what is the proper method and what is the timing to do the final sync?  

There is tons of conflicting information on the subject.  What is the official MS recommendation?

Answer 3

Hi Jmore10,

Thanks for your reply.

Generally, if you create a new batch, the duplicate emails may be a potential issue. Given the situation, if you want to move other emails, you may use PST files to finish it. I understand that it may not be a convenient method for many users. Therefore, it should depend on your actual environment.

Your understanding is highly appreciated.

Best Regards,

Erick

Answer 4

All records were changed and taking down the system again is not an option.

I have read so many conflicting reports on this subject.  What is the proper method and what is the timing to do the final sync.

Answer 5

Hi Jmore10,

May I know whether you change all NDS records (MX, autodiscover) to Office 365? If so, I suggest you stop the batch and change all NDS records back to the on-premise servers. After that, you can restart the batch. Generally, when you re-run the cutover migration batch, data which hasn’t been moved to cloud will be migrated again.

If it doesn’t work for you or you have any issues when doing that, please feel free to let us know.

Best Regards,

Erick