How to access resource account in Outlook (Windows) with SendAs Permission
You have been given SendAs permissions to an account and you want to compose an email in Outlook for Windows
Step 1. Click 'New Email'
Step 2. Click the 'Options' tab
Step 3. Click 'From' in the ribbon
Step 4. Click 'From' in the Message section then choose 'Other Email Address...'
Step 5. Input the resource account Display Name or Email Address and click the 'Ok' button
Step 6. You'll notice the resource account email address listed next to the 'From' listing