To delegate send as permissions for a user, do the following:
- Open up user properties, select the Mailbox tab, and click Mailbox Delegation.
- Use the Add/Remove buttons to modify the send as list.
- Click OK twice to apply the settings.
To delegate send as permissions for a group, do the following:
- Open up group properties, select the Office 365 tab, and click Group Delegation.
- Use the Add/Remove buttons to modify the send as list.
- Click OK twice to apply the settings.