Does anyone know if when sending a html newsletter what kind of support the major email clients have for the subject= and body= parts of the mailto tag?
The behavior varies by both email client and source application. Here's a likely enough example from my own system, using pjp's link.
<a href="mailto:[email protected]?subject=Hello%20People">Send Mail</a>
I tried the same link in HTML emails read by gmail and Yahoo web clients.
That much variation on just one computer makes embedded mailto tricky to use. I bet that's why many email newsletters provide a "View as a web page" link in the header.