Step 1:  Select the account icon in the top right corner



Step 2:  Select 'Account Settings'



Step 3:  Select 'Message Signature'


Step 4:  Enter your signature and/or default message and click 'Update.' This signature/message will automatically be appended at the end of all outgoing emails and can be edited in the Share panel prior to being sent.


Note: This signature shows up in the email message and pop-up box before the user opens the document.