It's not quite what you want, but it's possible using modern javascript to create an EML file on the client and stream that to the user's file system, which should open a rich email containing HTML in their mail program, such as Outlook:
https://stackoverflow.com/a/27971771/8595398
Here's a jsfiddle of an email containing images and tables: https://jsfiddle.net/seanodotcom/yd1n8Lfh/
HTML
Javascript
(function () {
var textFile = null,
makeTextFile = function (text) {
var data = new Blob([text], {type: 'text/plain'});
if (textFile !== null) {
window.URL.revokeObjectURL(textFile);
}
textFile = window.URL.createObjectURL(data);
return textFile;
};
var create = document.getElementById('create'),
textbox = document.getElementById('textbox');
create.addEventListener('click', function () {
var link = document.getElementById('downloadlink');
link.href = makeTextFile(textbox.value);
link.style.display = 'block';
}, false);
})();