Email was designed as a text-only format 40 years ago, and not a heck of a lot has changed. I may be a curmudgeon, but I don't want images, I don't want stylesheets, I don't want Javascript, and I don't want plugins. Email can come from anyone, anywhere, at any time, with any amount of malicious content.

Within Thunderbird, I compose all my email in plain-text and view messages with remote content blocked. Sometimes, though, I do have the occasional need to forward an HTML email from a trusted source. For as long as I can recall, I've been rifling through the main Settings menus, setting the Compose in HTML switch, forwarding the note, and then clearing the switch. It's a pain.

After years of Thunderbird use I finally learned that you can shift+click the Reply or Forward (or Reply-All) buttons and it will, for that message only, toggle HTML composition.

It's the small things in life.