To amend permissions on a mailbox, follow the steps below or watch the short video tutorial:
Log into the admin portal.
Within the Admin console, on the left-hand side, click Mailboxes.
Select the user to have the permissions amended for then click the Delegation tab.
Select the option that you need to amend the permissions for then click Edit.
Read and manage permissions - the mailbox is visible in another user's outlook alongside their own. They'll have full visibility of the inbox and sent items as well as the ability to send as the user.
Send as permissions - allows for the sending as the user from a new message window.
Send on behalf permissions - allows for sending on behalf of another user from the new message window.
Select the user to assign the permissions.
Click Save and then click Save again.