User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US) AppleWebKit/534.3 (KHTML, like Gecko) Chrome/6.0.472.63 Safari/534.3 Build Identifier: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100922 Thunderbird/3.1.4 No matter if you set HTML to be sent as your preferred format in Composition options, emails are sent as plain text, unless you specify you want HTML in the from "Options/Formatting..." editing window. Reproducible: Always Steps to Reproduce: 1. Set HTML as preferred format in Composition options. 2. Write a HTML message. 3. Send it. 4. Verify in Sent Messages that plain text was the actual format sent. Actual Results: Email was sent in plain text format, even though it had HTML set as default format. Expected Results: Send the email in HTML.