I'm pretty sure a html 3.5 subset is what's rendered by mail clients. At least, gmail uses font to change fonts, and span to change color. they were both ignore

I'm pretty sure a html 3.5 subset is what's rendered by mail clients. At least, gmail uses font to change fonts, and span to change color. they were both ignored. this was the raw string gmail generated: abc <b>def</b> <i>ghi </i><u>jkl</u><i> </i><font face=3D"comic sans ms, sa= ns-serif">mno</font><i> </i><font face=3D"courier new, monospace">pqr</font= ><i> </i><font size=3D"6">stu</font> <span style=3D"background-color:rgb(25= 5,0,0)">vwx</span><div>