Microsoft 365 : Send on behalf vs Send As

August 24, 2020


Microsoft 365 : Send on behalf vs Send As

First of all rights management in Microsoft 365 is confusing complex and does not allow the users to set permissions similiar to google. Coming from GSuite this really is a massive drawback which adds complexity users do not understand for absolutely no reason.

Send on behalf

Send on behalf basically means the user with send on behalf rights could chose the origin user in the from field. Once an email is sent Microsoft 365 automatically adds sent on behalf of. This might look similiar to the screen below in the recipients inbox.

To grant an additional person send on behalf right I always use this command

Set-mailbox $User -MessageCopyForSendOnBehalfEnabled $True 
Set-Mailbox $User -GrantSendOnBehalfTo @{add=$Rights}

It’s required to set the GrantSendOnBehalfTo rights like this otherwise the first one is overwritten as only 1 will remain. MessageCopyForSendOnBehalfEnabled means nothing else than the ofigin mailbox owner has a copy of the sent emails in the outbox. We do this to ensure full transparency to the origin mailbox owner.

Send As

Send As rights is basically a kind of impersonation. The recipient cannot differentiate on who has sent the email.

Set-mailbox $User -MessageCopyForSentAsEnabled $True 
 Add-RecipientPermission -Identity $User -AccessRights SendAs –Trustee $Trustee -Confirm:$False

With -Confirm:$true the user has to confirm the rights.

Unfortunately neither -MessageCopyForSendOnBehalfEnabled nor –MessageCopyForSentAsEnabled could be set in the mailbox plan.

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