HTML mail in Thunderbird

I am no fan of sending HTML mail. I have configured my mail client, Thunderbird to send out only plain text messages. However, today I needed to send out an article which contained lots of link. It turns out that you can always shift-click the "Write" button in Thunderbird and it will allow you to compose HTML mail.

Where I found this tip and a knowledgebase for mozilla products (a bit outdated, but still good)