Need add-on to maintain HTML format of outgoing mail

[Swarup]

I use TB on Ubuntu. Since 2014 I've been using an add-on called "Always HTML" to keep emails I write formatted as HTML. A couple weeks back it seems TB upgraded to 60.2.1, and since then my outbound emails all degenerate into generic text. When I check my add-ons, it says "Always HTML" is incompatible with TB 60.2.1. Is there another add-on that is incompatible, which can be used instead of "Always HTML". Or is there a way to get "Always HTML" to work with TB 60.2.1. Need a solution. Thanks!

[DanRaisch]

Check your settings under Edit → Account Settings->Composition & Addressing, confirming that "Compose messages in HTML is checked."
Check under Edit → Preferences->Composition->click on the "Send options" button and uncheck "Send messages as plain text if possible".

[Swarup]

The Account Settings were already as instructed by you.
The Preferences "Send Options" I had to update according to your instruction, and that seems to have taken care of it.
Thank you!

[DanRaisch]

You're welcome.

[makaiguy]

The option to "Send messages as plain text if possible" was added in version 45. Without "Send messages as plain text if possible" checked, it works like this:

• When you send a message composed in HTML mode, TBird "auto-detects" whether you actually USED any HTML features (change font, color, or size, insert a table or image, etc.). For these purposes, Bold, Italics, and Underline are not considered to be HTML since there are standard plain text equivalents it can use for them: *Bold*, /Italics/, and _Underlined_. If it auto-detects a message you were sending did not actually use HTML features, it just converts it to plain text to save on message size, and sends it off that way. Your "Sent" copy would reflect what the message looked like when it was actually sent.
  
  You can change this behavior for a given message via the Options | Delivery Format menu option (only available when composing in HTML mode). This option applies to how the message will be treated when it is sent, not how it will be formatted during composition. The "Auto-Detect" setting is the default and performs as described above. If you compose in HTML and want to force it to go in HTML even when you don't use any HTML features, you can change this to one of the HTML options. This is only good for that message and returns to the Auto-Detect default on the next.

Another way to force a message composed in HTML to be sent in HTML even when you don't use any HTML features is to attach an HTML-formatted signature that DOES use HTML features other than bold, italic, and underline. I just include a blank space where I have changed the space's text color to white.