Moving an email address between on-prem AD accounts synced with AAD/EXO?

[LRSFC_DanJ]

We’re currently reviewing our staff leavers process. One of the suggestions that leadership has come up with is, when a staff member leaves, could we move their email address (note: NOT their mailbox) to another mailbox which has an autoreply set on it telling people this person no longer works for us?

 

Our accounts are on-premise AD accounts with mailboxes in Exchange Online, synced via Azure AD Connect, so this doesn’t seem as straightforward as I might otherwise have thought.

 

Does anyone know how long we have to wait between removing the email address and proxyAddress from the source AD account, before it can be added to the proxyAddresses in the destination AD account?

 

Or, is there a different way we should be thinking about this?

[ThomL]

I've removed an email address from one AD user (email field and Proxyaddress), forced a delta sync to 365, then once sync has completed added the email address to another AD user's proxyAddress attrib. then forced another delta sync and not had any issues - new user has new alias email address. Although in this case I did remove the original user from being synced to Office 365 - not sure if that has an impact on this process. All in all - a max of 5 mins for this process I'd guess?

 

Make a couple test accounts and give it a go!

 

**Edit**

 

I force syncs and watch them progress from the server that we have Azure AD Connect installed with this PowerShell:

Write-Output "Office 365 Delta Sync Starting..."
Start-Sleep -Seconds 2
Start-ADSyncSyncCycle -PolicyType Delta

Write-Output "Sync Started - Opening Synchronization Service GUI"
Start-Sleep -Seconds 2
Start-Process "C:\Program Files\Microsoft Azure AD Sync\UIShell\miisclient.exe"

Edited October 17, 2023 by ThomL

[chaplic]

I think you're over-egging it. Remove the proxyAddress from the leaver, add it to the generic account and that's it. It's possible you'd get a sync error for a dup, but that would sort itself out on a second sync.

 

Note of if you are using out-of-office it would only fire for a recipient when they email the first leaver.

[psydii]

We move them to the A1 license, hide from the address book, and set an auto reply. A few months later they get added to a group that has a transport rule configured to hard block mail delivery to the mailbox. Some time later (depending on the ex-colleague's former role in the school) we remove their licence and the mailbox and onedrive get purged.

[MatthewL]

Surely if a user is deleted mailbox doesnt exist anyone that attemps to email will get a none deliverable, this should be enough?

[LRSFC_DanJ]

Surely if a user is deleted mailbox doesnt exist anyone that attemps to email will get a none deliverable, this should be enough?

 

Unfortunately leadership says they want an actual reply saying the person doesn't work here any more.