A quick break down of the environment where this issue occurred
- Office 365 in Hybrid with Exchange 2016
- Local 2019 AD Domain with Azure AD Connect syncing to Office 365 every 30 minutes, with no AD write back
- 350+ could mailboxes with 2200+ still on prem
I recently had an issue at work with my Exchange online mailbox not being able to pull free busy information from any of my company’s onprem mailboxes. My mailbox was migrated a little over 2 years ago and I’m not exactly sure when it stopped, but I only noticed as my company started to enact it’s return to work plan early in the summer of 2021 and I couldn’t see the free busy information of any of our conference rooms. All of which we haven’t migrated to Exchange Online yet. At first, I checked in with my teammates and discovered the issue was just with my account. From there I tried using the Microsoft Remote Connectivity Analyzer to troubleshoot, but got a generic error when attempting the various Exchange tests. I then checked for any odd attributes set on my account, but that turned up nothing obvious. I then tried doing a New-MoveRequest PowerShell cmdlet, which sometimes helps with fixing odd issues in Exchange Online. The hope in doing so is that the post move validations might correct whatever was causing the free buys look up issue. So, after exhausting all the options I could think of I opened a ticket with Microsoft Support. After going through the normal troubleshooting steps, they suggested that I clear out the following AD attributes and wait for a sync from our on premises AD to Azure AD
- msExchRecipientDisplayType
- msExchRecipientTypeDetails
- msExchMailboxGuid
Before clearing these attributes, I made a note of the values and then waited for 2 Azure AD connect sync session. Unfortunately the issue persisted and my companies various other integrated SAAS platforms were throwing errors since those attributed weren’t populated for my account. At first, I tired running the Update-Recipient PowerShell cmdlet in both Exchange Online and Exchange on premises to see if it would re-populate those attributes. Sadly it did not so I added back the values I saved for each. About 24 hours later I checked if the issue was still present, and it was fixed! MS support wasn’t exactly sure why the issue was resolved, but the next time I run into an odd Exchange issue I’m going to try clearing those attributes first.
