[quote user="Goody"]So far, I have found only one client that does all this and much more. The only thing is HTML seems to get it problems. HTML must be a difficult thing to process in email clients.[/quote]
It's difficult in and of itself. One of the problems is that HTML parsers, unlike XML parsers, are designed to be "forgiving". XML parsers are supposed to stop parsing when encountering syntax errors:
[quote]Second, XML has draconian error-handling rules. In contrast to the leniency of HTML parsers, XML parsers are required to fail catastrophically if they encounter even the simplest syntax error in an XML document.[/quote]
http://webkit.org/blog/68/understanding-html-xml-and-xhtml/
I guess the web would not have grown as phenomenally fast as it has if the people who coded web browsers hadn't tried to be lenient in their parsing, working around errors and trying to second-guess what someone had "meant" when he made an error in his page. It's meant anyone and everyone can put up something written by hand in a slapdash suck-it-and see way in Notepad or in poor WYSIWYG tools that write dodgy HTML. And there's a kind of vicious circle here.
But the result is that HTML parsing is a bit of a mess. How should a browser handle some error that someone should not have made in the first place? It's anyone's guess, and the error-handling of every browser is different. Should you give someone what he's (literally) asked for when that makes no sense, or guess that he's got a conceptual misunderstanding here that's not uncommon, and that Internet Explorer has made allowances for, so that you'd better do the same? It makes browsers even more complex than they need to be and even larger. Have you seen the size of Firefox these days? And don't even ask about Internet Explorer.
There's also the matter of proprietary extensions to the HTML standards--though that's perhaps less of a problem than it was. However, it's certainly a problem in email. If you check the box to use Word as the editor in Outlook you end up sending very bad HTML full of gibberish that is not part of any official HTML standard known to the W3C.
[quote]The Bat does a terriable job with HTML[/quote]
I didn't know that. But you can't blame it. It's not easy to do. Outlook Express uses Internet Explorer to do HTML parsing, and that's a full-blown browser, so naturally that's going to do a more polished job. However, the down side is that that's probably not a very safe thing to do--all that complexity and functionality brings security problems with it. (However, OE does, these days, at least use the "restricted" Internet Zone in IE by default; it used to run scripts and all sorts of nonsense, which is why malware used to go through it like a dose of salts.)
In Office 2007, Microsoft has, apparently, switched to using Office's HTML viewer (the one used for Word) instead of IE for Outlook. I don't know why they made the change, but it will make Outlook less capable at displaying HTML.