Pleased to oblige!
What is X-Bonus?
X-Bonus is the daily quote, a bonus feature of AWAD. The reason the quotes are called X-Bonus, is historical. Previously, the quotes used to appear in the email headers. Internet conventions require that non-standard headers be preceded by an X (for eXperimental) and the name became X-Bonus. Even though the quotes have come down to the message body, the name X-Bonus continues.
From the A.W.A.D. FAQ.