Exchange Online: Add-MailboxPermission Without Automapping (Powershell)
Add delegated access to another Exchange Online mailbox to a user without automatically mapping the mailbox in Outlook. Allows SendAs to save sent mail in the delegated mailbox’s sent items folder, instead of the user’s sent items folder.
the Problem
When you add delegated permissions to a Shared Mailbox in Exchange Online, the mailbox is automatically added in Outlook, but sent email is stored in the users sent items instead of the shared mailbox sent items.
the Solution: Powershell to the Rescue
The only way to disable automapping is via PowerShell. The relevant bit here is -AutoMapping $false.
Edit these values to adjust the script below:
Connect-ExchangeOnline # Or, if you want to access a delegated org:Connect-ExchangeOnline
-DelegatedOrganization
NameOfTheOrg.onmicrosoft.com # Complete the login in your browser # first, you'll want to remove existing permissions for the user:Remove-MailboxPermission
-Identity NameOfTheSharedMailbox
-User username
-AccessRights FullAccess # Then you'll want to re-add the permissions, this time with automapping $false:Add-MailboxPermission -Identity NameOfTheSharedMailbox -User username -AccessRights FullAccess -AutoMapping $false… and that is it.