Here are the steps to perform in Microsoft Outlook, to add a Shared Mailbox email address to your From field:
- Select the New Email button to start composing a new message
- If necessary, select the Pop Out button in the upper right, to get the new email in its own separate window
- Select the Options tab in the top ribbon
- Select the From button, to show the From field
- Select the From dropdown, next to the Send button
- Select Other Email Address... at the bottom of the dropdown
In the Send From Other Email Address pop-up, select the From... button- Search the Address Book for the Shared Mailbox address you wish to send From
- If the Address does not appear in the Address Book, you cannot send messages From that address
- Select the address, and click OK
- Click OK on the Send From Other Email Address pop-up
- The address you wish to send from should now be in the From box in the email composition window. From now on, the From drop-down will be visible, and you can choose which address to send From for each message.