Email routing O365 Exchange

abhijitm00
abhijitm00 used Ask the Experts™
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We have migrated an email domain xyz.com from an Exchange 2010 server to O365. We have other email domains on this Exchange server. All external email is going fine to mailboxes in O365. Internal email originating from the Exchange server from other domains is not reaching mailboxes in O365 but still reaching their old mailbox on Exchange server.

I have hidden the mailbox of xyz.com's users in Exchange, removed xyz.com as Authorative domain from Exchange server, created a send connector to bypass anti-spam filter and send email destined for xyz.com directly using MX record. But emails from other internal domains are still being recieved only on Exchange server not on  O365

Please advise any steps I can take to troubleshoot further

Thanks
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Commented:
You need to convert the migrated mailboxes to Mail Enabled Users and populate the targetAddress with the onmicrosoft.com alias of the Office 365 mailbox.

Author

Commented:
Thanks Jason. To convert them to mail enabled users do I need to delete their mailboxes on Exchange server to do this?
Commented:
Someone already wrote a script for the entire process:

https://gallery.technet.microsoft.com/office/How-to-convert-mailbox-to-c92c9153
Adam BrownSenior Systems Admin
Top Expert 2010

Commented:
Change xyz.com from an Authoritative domain to an Internal Relay domain or make sure the users have their .onmicrosoft.com email address as a targetaddress in their AD Attributes (Jason Crawford's script should do this for you). Once users are migrated to O365, they should not have a mailbox on-prem. If the migration was done as a Hybrid Move instead of a cutover or staged migration, this should be done automatically.

Author

Commented:
The script worked. Thanks Jason and Adam

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