Apply Mailbox Permissions in Office 365


If you need user to manage the mailbox of an another user or sent out as them, you will need to grant the user permissions over that mailbox. Exchange Online allows the following permissions to be set up:

Read and Manage: Also know as Full Access, allows another user to view and manage the contents of the user’s mailbox. These permissions allows emails to be read, moved and deleted, but does not allow emails to be sent out as the user.

Send As: Allows one user to send as another. To the recipient, an email sent this way will appear to have been sent by the other user. The Sent Item will still be placed into the original user’s mailbox.

Send on behalf: Allows one user to send as another. To the recipient, an email sent this way will show both the original sending user and the user they were sending for. The Sent Item will still be placed into the original user’s mailbox.

NOTE: Permissions are added onto the source account. For example, if you want User A to send as or manage the mailbox of User B, then permissions will need to be added onto User B’s mailbox.

Apply Mailbox Permissions

  1. Log into your Microsoft 365 Admin Center at https://admin.microsoft.com

  2. Go to ‘Users > Active Users’

  1. Select the user to apply forwarding from

  2. Select the Mail heading

  3. Under Email forwarding, select Manage mailbox permissions

  1. Next to the permission you want to grant, select Edit

  1. Select Add Permissions

  1. Tick the checkbox next to the user(s) you want to give permissions to

  2. Press Save

  3. Press Close


Permissions can take a while to propagate. If you recently made these changes, please allow up to an hour for them to process.