Migrating Subsidiary Company from Exchange to Office 365

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