Math formulas in emails

Is there a way to enter LaTeX (or similar) formulas into an E-Mail and get them rendered as typeset formulas on the receiving side, perhaps with cooperation of the receiving party? My preferred mail client is Thunderbird, but solutions for other applications might be of interest as well, and portable solutions obviously would work best.

Things I'm hoping for but couldn't find so far:

• A way to reference the MathJax JavaScript files from within a HTML E-Mail, together with a configuration on the client side which allows execution of this particular JavaScript without opening too much of a security hole.
• Some add-on which enables MathJax on the receiving side, without any particular reference to it in the E-Mail. This might work even for plain text messages, which is a good thing.
• Some add-on which alloes the user to enter LaTeX code somewhere, and which embeds the corresponding MathML into a HTML-formatted message.
• Some add-on which allows me to mark part of my message before clicking a button. The marked text should then be interpreted as LaTeX and be replaced by the corresponding MathML. Obviously this will only work for HTML-formatted messages, too.

I'm interested in any known procedures along the lines above. In cases where not immediately obvious, information as to which applications on the sending as well as on the receiving side support this approach would be welcome. For example, I have heard that both Thunderbird and Apple Mail will support MathML for received mails, but Outlook will not. At least the part about Thunderbird rendering the formula I can confirm.