How to Grant Permissions to Other Office 365 Mailboxes?

Megha Sharma Megha Sharma Updated On - 25 Oct 2019

Microsoft Office 365 allows to assign mailbox delegate permissions like Read and Manage, Send as and Send on behalf to other users. These permissions are assigned to other user mailboxes via Office 365 admin center or Exchange Online PowerShell cmdlets.

Let us know what these permissions are:

Read and Manage: This permission allows the assigned user mailbox(es) to read as well as manage emails in the user mailbox on which the permission is assigned.
Send as: This permission allows the assigned user mailbox(es) to send emails from another user’s mailbox on which permission is assigned.
Send on behalf: This permission allows the assigned user mailbox(es) to send email on behalf of the mailbox on which permission is assigned.

Assigning Permissions to Another User Mailboxes via Office 365 Admin Center

Now, that you know what permissions a user mailbox can assign to other user mailboxes, let us know the procedure:

  1. Log in to your Office 365 account and click Admin.
  2. Then, go to Users>Active Users. Double-click on any desired user and then under Mail Settings section, click Edit option against Mailbox permissions.
  3. A new page Edit mailbox permissions will get open. Here, to set permissions for user mailboxes, click Edit against Read and manage feature.
  4. Click +Add permissions to add the user mailboxes whom you want to assign this permission.
  5. Select the desired user mailboxes from the list and then click Save.
  6. Thus, user mailboxes are assigned permissions.
  7. Similarly, you can assign Send as and Send on behalf permissions to other user mailboxes.

Assigning Permissions to User Mailboxes through Exchange Admin Center

You can also set permissions for the selected user mailboxes via the Exchange Admin Center.
Now, head on to the steps through which you can assign these permissions.

  1. Open your Office 365 account with the login credentials.
  2. Click Admin and then open EAC by navigating to Admin centers>Exchange.
  3. In EAC, click recipients and then select mailboxes option. Then, select the desired mailbox and click the Edit icon.
    Note: You can select multiple mailboxes and under Bulk Edit on the leftmost pane, click More options and choose Mailbox Delegation option to assign the permissions to mailboxes simultaneously.
  4. Now, select mailbox delegation option from the left pane and then click + icon under Send As to select the user mailboxes and assign them this permission.
  5. Select the user mailboxes to which you want to assign this mailbox permission, click add -> and finally click OK to add them.
  6. Likewise, you can assign other mailbox permissions like Send on behalf and Full access.

Another way to assign these mailbox permissions to the Office 365 user mailboxes is the use of PowerShell cmdlet.

To run the PowerShell commands for assigning the permissions, you need to connect to Exchange Online first.

Connect to Exchange Online

  1. First, run the Windows PowerShell as administrator (right-click on the application icon and choose Run as administrator option).
  2. Run this command.
  3. $session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri “” -Credential $cred -Authentication Basic -AllowRedirection
  4. Enter the Office 365 global account credentials in the opened window.
  5. Now, run this final command to connect Exchange Online to PowerShell.
  6. Import-PSSession $session

Assign Mailbox Permissions with PowerShell cmdlets

  1. To assign Send As permission to a user mailbox, run this command
  2. Add-RecipientPermission <Identity> -AccessRights SendAs -Trustee <Identity>
  3. Assign Send on Behalf permission to a user mailbox with this command
  4. Set-Mailbox <Identity> -GrantSendOnBehalfTo <Identity>
  5. Assign Full Access permission to single user mailbox with this cmdlet.
  6. Add-MailboxPermission <Identity> -User <Identity> -AccessRights FullAccess -InheritanceType All

So, we have discussed these manual techniques to assign mailbox permissions to the Office 365 user mailboxes. Some users with technical knowledge may find it easy to perform while other users might find it difficult to operate especially while dealing with the PowerShell commands.


Office 365 Admin Center and Exchange Admin Center offer options to assign mailbox delegation and access rights to the user mailboxes in Office 365. Running PowerShell cmdlets is another option but needs some expertise.