Exchange migration: Problems bringing mailbox back on-premises(normally works)

Question

We just started using Exchange Online and it has been working great. Our current plan is to use Exchange Online, but when someone quits our company we will migrate the mailbox back on-premises for a few months, to free up licenses, and then delete the mailbox 4 months later once we confirm that their boss, etc has not requested access to their email, etc.

Normally, I can migrate mailboxes back on-premises with no issues, but now I have 1 that is stuck ay syncing for days. Does not matter if I use Exchange Admin Center, powershell, etc the mailbox never migrates 100%. This is not normally an issue, but have increased the error count for this mailbox, etc and it just stalls. Anyone have any ideas or know of some good logs I can look through, etc.?

Answer 1

Have you checked the service health in the portal to see if there are any issues?

But..... Why migrate the mailbox back?

Simply convert the mailbox to a shared mailbox and then remove the license. You can remove the account from the Azure sync later when you want the mailbox removed.

https://learn.microsoft.com/en-us/microsoft-365/admin/add-users/remove-former-employee?view=o365-worldwide
https://learn.microsoft.com/en-us/microsoft-365/admin/email/convert-user-mailbox-to-shared-mailbox?view=o365-worldwide

Answer 2

Great suggestion on the converting to shared mailbox, and releasing the license

Answer 3

Service Health and Azure AD Health are completely clear, but not sure why the mailbox will no longer offload.

Thanks for the suggestion about converting them to Shared mailbox. I knew that was possible, but never thought it might be a smooth way to stop paying for a mailbox while it is being decommissioned