How do I get Exchange Online GUIDs to write to Active Directory
Posted by Phyber05@reddit | sysadmin | View on Reddit | 7 comments
We are a hybrid AD join, using Azure AD Connect, and also have an on prem Exchange 2019 server.... I have migrated most all mailboxes up to Exchange Online and mail is flowing...
However I'm noticing that since the mass migration, mailboxes created solely in Exchange Online aren't email-able by users/systems still on prem Exchange 2019.
I have checked my Azure AD connect and added the msExchMailboxGUID attribute to sync, but the text reads like it's only a one way sync from AD -> Entra ID.
Am I doing this wrong? How can I stop manually updating this field in AD?
datec@reddit
You have to run a command on all new accounts that you create. I think it's enable-remotemailbox but verify that first. You have to do this if you are going to keep routing mail from on premises servers. You don't have to do this if you create the exchange online mailbox from an on-prem exchange server. You will have to continue to do this until you remove the hybrid AD connector, because you must manage mailbox attributes on-prem while still hybrid. The only way to fully manage mail attributes in the O365 is to disconnect on-prem AD.
Sorry for the formatting, on mobile.
Phyber05@reddit (OP)
Thank you! I’d run that against Exchange Online, and it would write down to my Active Directory?
datec@reddit
You run it on your on-prem server.
mysterioushob0@reddit
I think Ive ran into this and it was a mix of making sure the Global Contact List was updated with the new emails and checking the ProxyAddress Attribute in ADUC. Whats the NDR code from the bounceback when Exchange 2019 emails Exchange Online?
Phyber05@reddit (OP)
This is the top error section:
Remote Server returned ‘550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup’
titlrequired@reddit
They are fully cloud only? No synced on prem user?
Domain is authoritative on prem?
Phyber05@reddit (OP)
Hi! So I create the user account in AD, and when the user is synced via Azure Connect, I assign them a 365 license, then their Exchange Online mailbox is auto created.
Previously, I was making the user in AD in an OU that didn’t sync to 365, then creating the users mailbox in my on prem Exchange 2019, then move the user out of that temp OU and let sync, then manually migrate their mailbox off the on prem Exchange, and assign license. I’m looking to streamline my setup process.