These tools are fine for companies and those who market products as they've resources to throw at the problem. My complaint however is with normal email clients

These tools are fine for companies and those who market products as they've resources to throw at the problem. My complaint however is with normal email clients as every one that I've used has had a notoriously bad message/HTML editor. It's as if programmers of email clients object to any formatting in messages other than plain text. For example, Thunderbird's editor is notoriously bad, it not only generates bad and quite buggy HTML (especially in long emails with many edits) but it also lacks the ability to edit simple HTML formatting stuff such as tables, line spacing etc. The many problems with Thunderbird's message editor are not new as they have existed for many years. Surely if email message formatting was of concern to its developers then they would have made attempts to fix them over the past two decades. Clearly it's not. This bloody-mindedness even extends futher than that, there is so easy way to switch to an external HTML editor and back. The best one can do is to use a third-party plugin that switches to HTML view and then one is left to one's own devices. That may be OK for those of us who know HTML but it sure isn't convenient. And users who don't are left with the defaults of Thunderbird's brain-dead editor, which is unfair. Moreover, in this day and age they shouldn't have to know how to edit HTML just to send email with adequate or appropriate formatting. In essence, we first have to contend with all these HTML issues long before we're even at the point of considering let alone actually incorporating CSS. Limiting the formatting options in email messages has to be a deliberate policy decision by email client developers, especially so those who develop clients based on browsers (Thunderbird on Firefox/Mozilla etc.), for in comparison to their editors these browsers have superb rendering engines yet client developers never take advantage of them. We know this is possible because the HTML editor Bluegriffon does a very good job of using (incorporating) the Mozilla engine. I'd even be content if Thunderbird allowed me to use Bluegriffon as an external editor but it's not possible with all recent versions of the client. I find this highly annoying as there's no choice in the matter, I cannot just scrap Thunderbird and buy some exotic client simply because there is no suitable product available anywhere. I cannot understand why this situation has existed for so long. Why can't I do advanced formatting in emails when clients such as Thunderbird are quite capable of rendering advanced pages with their inbuilt browsers? Surely I'm not the only person who'd like to put stuff such as math formulae into emails but we're nowhere near that point of development with email clients. Email messaging formatting still resides in the Dark Age and those responsible ought to be damned ashamed of the fact.