Where can I find detailed, systematic HELP for advanced topics relating to Thunderbird?

Question

In moving from XP to Windows 7, I opted for Thunderbird as email client in order to bypass Microsoft's hyper-intrusive Windows Live Mail (I used Outlook Express for years).
I have a very complicated email structure, and it's taken me weeks (seriously) to learn how to replicate it in TBird. Now I'm trying to customize TBird further, but none of the TBird articles/forum Q&A's/Google searches address my questions.
There is no live tech support for TBird, and I'm just about ready to leave it for good. However -- one last effort: where can I find detailed, systematic HELP for advanced topics relating to Thunderbird?
Thanks.

Answer 1

I am no expert, but I don't know of any authoritative reference as to what elements of HTML and CSS are supported in Thunderbird. However, as I believe you appreciate, it's more than just what Thunderbird supports, but one must also think about what is likely to work in other email clients. Keep it simple. Avoid ancient deprecated tags that other email clients may not support, and for similar reasons, avoid cutting edge technology. Remember that recipients using tablets or smartphones won't appreciate large fancy email documents.
The only thing ''guaranteed'' to work in email is plain text. ;-)
If you haven't already discovered it, the Stationery add-on is designed specifically to support OE stationery in Thunderbird. Your existing stationery may "just work" in this add-on. It makes switching between various stationery templates much easier, but I'm not confident that it will affect interpretation of your CSS or HTML coding.
Your code is at least clean and minimal. Most times my involvement with troublesome templates and signatures centres on the horrible bloat and mso custom code generated by Word or Outlook.
Having said that, you and I are mortal enemies, as I don't have much patience with what you aspire to achieve. I specifically don't like background images, nor being obliged to suffer other folks' bizarre choice of typefaces and colours (but your simple 12pt black Tahoma is quite inoffensive. ;-) ) I'm of an age where my tolerance and eyesight are easily offended.
Nonetheless, I'm intrigued by how to parse the tag for the background image, as it doesn't look like a legitimate pathname to a graphics file. Does the background image actually appear as required?