Set up Custom Security Question
Under that you can set a custom default question such as what are the last 5 digits of your SSN?:
Click the Save button at the bottom of the screen.
Now when you go back to New Transfers you will see the delivery options where you can use the saved question or enter a different custom message if preferred:
Once you've added a recipient, subject, message and entered the "Answer" Click the Add File(s) button
Select the file(s) you wish to send and click Upload and send now.