nate: Yes that is true, but the data is only encrypted from your browser to the webmail server. What Mauricio is talking about is the delivery of the email from the sender's computer to your email server.
My concern is what are you sending/receiving that is sensitive? I've seen it too often, clients transferring sensitive info such as credit cards via email. While the possibility of interception is low, it is still a very silly mistake to be making.
Nate I appreciate your [& Mauricio's?] point that the receipant may not be using a secure email such as https. s-mime or PGP end to end. Rest assured I would never send sensitive data such as a credit card or passwords via normal email.