Sorry if this has already been mentioned in another thread, but I just noticed that Gmail now has an option to always establish a persistent HTTPS connection regardless of the URL. Previously, it was necessary to explicitly include the https:// protocol in the URL (e.g.,
https://mail.google.com/) to maintain a persistent secure connection to Gmail. Now it's an option at the bottom of the General tab on the Settings page.
Always do what you can to authenticate and secure your email!