Send a single HTML email from Thunderbird, overriding the default "plain text" setting

I do not like HTML emails. Because of that, I've set my Thunderbird to compose emails as plain text.

But, in some rare cases, I have to send an HTML email, e.g.:

Hi Your Majesty, the button you are asking for is the one with the plus and the minus on top of each other:

Let me know if that helps. Cheers!

Writing such simple stuff into a graphical attachment slows everything down on both sides, so I think in this rare case, HTML can be justified.

Is there any method in Thunderbird to compose a single, one-off email as HTML?

I know that I can configure it to compose all emails as HTML, so using that I would have to switch it on, compose the email and switch it off again. Not good.

Solution 1:

If your default setting is to compose Plain Text emails, hold down the Shift key when you click the Write button or Reply/Reply-All/Forward button. This will open a window to compose an HTML email.

Solution 2:

Another possible solution is to select the box

Account Settings -> Composition & Addressing -> "Compose message in HTML format"

and also select

Tools -> Options -> Send Options -> "Send messages as plain text if possible"

Then when you open a composition window, you'll see the HTML formatting bar (font size, bold, italics, etc.), but Thunderbird will only send your message as HTML if you use one of those options (or if you're replying to an HTML-formatted message). If you compose a plain-text message with no formatting, Thunderbird will detect that and send the message as plain text.