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Migrating Subsidiary Company from Exchange to Office 365

Copper Contributor

Hi

 

The Parent Company has an On Premise Exchange Server 2010. It owns several other Companies that all use the same Exchange Server with different email domains. One of these Companies is separating away and wants to move to Office 365. What would be the best migration option for this?

 

Could I do a Cutover Migration in this scenario, by giving the Migration Account FullAccess ONLY to the Mailboxes of the Company that is moving to Office 365 - Would this be possible? Cutover normally brings everything and I've never done it by just trying to do a subset of mailboxes.

 

PST or Third Party Tools are other options I assume.

 

There are about 400 mailboxes averaging around 3GB. No Rooms, Resources, Groups

 

Thanks

9 Replies
best response confirmed by Lee Walker (Copper Contributor)

Hi,

Does this company already has a hybrid connection in place?

Then you could do it with a remote move migration.

BR

Hi

 

I have installed the Office 365 Hybrid Wizard and using the new Express Minimal Migration method.

 

https://support.office.com/en-gb/article/Use-Minimal-Hybrid-to-quickly-migrate-Exchange-mailboxes-to...

 

Seems to be going well so far.

 

Thanks

Lee

Well that's the way to go.

Migrate via the hybrid connection...


BR

Hi Lee,

 

I am intrested to know when migration is finished and post migration behavious. Could you please keep us posted because i have never done Minimal Hybrid.

 

Regards,

Kamal

Still going ok.. Had a couple of issues I thought I'd mention, probably basic stuff but I'm not too experienced:

 

- Had to add the domain names into the Allowed Domains List in Exchange Online Admin Center > Protection > Spam Filter. Because it was starting to put Mail from on premise users into migrated users junk. This may be because the on premise sends through a Third Party.


- A couple of users didn't have a proxy address for <domain>.mail.onmicrosoft.com I think these were new starters which explains why the HCW didn't add the details.


- I cancelled a Batch from the Office 365 > Users > Data Migration > Exchange, because some had errors. But when I tried to start again, it kept failing. After I left it a while (Exchange TTL I believe) most of them worked. Two didn't appear to have worked because it said Failed in the Status section, so I re-ran and still kept failing saying "InvalidRecipientTypeException: Unsupported recipient type ‎'Mailbox‎' provided. Only ‎'Mailuser‎' is supported for this migration type." I checked with the users and they seemed fine (they were using Outlook and had the message saying the Administrator has made a change so close and re-open Outlook) and having looked in Exchange Online they had been migrated. So it was just the Status on the Data Migration page that was wrong - Manged to get the status to say Completed by simply deleting the Migration Batch. Lesson learnt - Don't cancel a Migration Batch - If there is an error with one, then let the others finish.

 

Aside from that, it seems straight forward. I had to do contacts and groups manually. There are no rooms/resources for me to do.

 

Oh, and there's no waiting at 95% sync. When you Start the Migration, it will go through and switch as well, whereas I remember the Cutover Migration waits at 95% sync until you finalize.

 

Regards

Lee

Hi Lee,

 

Many thanks for your feedback and experience to others on this community.

 

Congrats !

Thanks Lee for the insight. Sorry for the late reply as i was away.

 

Regards,

Kamal

@Stephan Bisser 

How would i preform this if  parent company is being nasty, with the situation. wanting Our company to do this manually and within two weeks ? afterward they shut down there servers. we cant access any of the important things to complete steps can you please point me in the right direction. Company A wants Company B out by a certain time, (2wks) but only gives out XL of name files phones and mailboxes   Please help

1 best response

Accepted Solutions
best response confirmed by Lee Walker (Copper Contributor)