I have discovered a hidden feature on Jetbits, called 'Mailbox'.
It allows Jetbits users to send emails to non Jetbits users.

If you want to use this feature, click this link to open the main page:

http://jetbits.com/inbox/?p=mailbox

The email address provided is in the following format:
(username)@jetbits.com

Conclusion: If you have a Jetbits account, you also have an email address that no one has told you about until now.