Good news for Office 365 Hybrid Customer – Delegate Access is now possible for cross-premises Mailboxes

Hybrid customer always complaint about the fact that Office 365 users not being able to delegate access to On-prem (Or) On-prem users not being able delegate to Office 365.

The good news is that Microsoft started allowing this feature from April 2018.

To enable cross premises delegation you first need to configure:

  • For on-prem user to become a delegate of an Cloud user

Set-OrgnizationConfig -ACLableSyncedObjectEnable $True

  • For cloud user to become a delegate of an on-prem user

msExchRecipientDisplayType attribute for the remote mailbox in on-prem AD to be set to -1073741818

       Get-ADUser -Properties msExchRecipientDisplayType |         where {$_.msExchRecipientDisplayType -eq -2147483642} | Set-ADUser -Replace            @{msExchRecipientDisplayType = -1073741818}

Now you can ask the user to use their outlook to allow the delegation.  Send-AS and on-behalf also works as per the below article



Hope this is useful.