To start using the Send As feature, create a new message in Outlook and click the From button in the new message, which displays an address list where you can select the mailbox that you want to send from.
By default, the From field is hidden when composing messages. To show the From field:
- Click New Email > Options > From.
- In Outlook 2007 and later, it can be enabled in a new message in Options > Fields > Enable Show From.
Note: if you are receiving the You do not have the permission to send the message on behalf of the specified users error message, select the Send As address from GAL rather than type it manually. To do that:
- Click on the From field and select Other Email address
- Click From
- Make sure GAL is selected as the Address book
- Find the user in the list and click OK