Getting email to appear in another email client in a preferred way is difficult, as the recipient's email client may be set to format the message differently, such as plain text instead of HTML or a different font. Other clients may display quoted text differently. For example, I have TB set to show different levels of quoted text in different colors. Gmail has settings for quoted text and possibly your recipients would benefit by exploring those?

OK, the "problem" appears to be that Thunderbird's default email template doesn't include any style info for the blockquote element, and Outlook and GMail default is to do rather stupid things with it. Outlook is especially bad: it simply does an indent, and the result is that it's impossible to tell the difference between quoted text and indented text.

This looks like a job for a template that includes some styling for blockquote...

Getting email to appear in another email client in a preferred way is difficult, as the recipient's email client may be set to format the message differently, such as plain text instead of HTML or a different font

That's not a problem. If the message has the proper css, it will be fine. It has always worked when sending e-mails with previous e-mail clients.

Other clients may display quoted text differently. For example, I have TB set to show different levels of quoted text in different colors. Gmail has settings for quoted text and possibly your recipients would benefit by exploring those

Something that doesn't work with "out-of-the-box" Outlook and GMail settings is a non-starter. I can't demand that the recipients of e-mails change their configurations. I need to get Thunderbird to send messages that work with the default settings for Outlook and GMail.

This looks like a job for a template that includes some styling for blockquote...

From what I've read, Thunderbird won't use a custom template for replies, is that correct?

How do I change the default template/css?

lets start with just exactly how much support for CSS the recipient has, like gmail ignoring CSS anywhere but in the head. This is not as simple as it should be because everyone thinks they know what is and is not risky.

Before you get to involved in the process, I suggest you have a look at the campaign monitor guide. They make a living on CSS in email essentially so I use them extensively as a source of mail formatting compatibilities. They have a vested interest in getting such things right. https://www.campaignmonitor.com/css/selectors/class-chaining/

This addon may already do what you want. The source on github may be a source of inspiration if it does not. https://addons.thunderbird.net/en-US/thunderbird/addon/quotecolors/?src=ss

This addon allows external style sheets. https://addons.thunderbird.net/en-US/thunderbird/addon/smarttemplate4/?src=search

lets start with just exactly how much support for CSS the recipient has, like gmail ignoring CSS anywhere but in the head. This is not as simple as it should be because everyone thinks they know what is and is not risky.

I've created a template message with css that works fine on GMail and Outlook. That covers 99+ percent of my correspondents. If anybody is using a client that ignores my css, then I'm no worse off than I am now.

Before you get to involved in the process, I suggest you have a look at the campaign monitor guide. They make a living on CSS in email essentially so I use them extensively as a source of mail formatting compatibilities. They have a vested interest in getting such things right. https://www.campaignmonitor.com/css/selectors/class-chaining/

Thanks, I'll definitely check that.

This addon may already do what you want. The source on github may be a source of inspiration if it does not. https://addons.thunderbird.net/en-US/thunderbird/addon/quotecolors/?src=ss

I saw that, but was under the impression it only affected how things were displayed locally and didn't alter the style of messages themselves. I probably misunderstood.

This addon allows external style sheets. https://addons.thunderbird.net/en-US/thunderbird/addon/smarttemplate4/?src=search

Yep, I saw that and was pretty sure it could do what I wanted — along with hundreds of other things :) I also suspect I can create an extension that will insert some css into a compose message quicker than I can figure out how to use SmartTemplates.

This addon may already do what you want. The source on github may be a source of inspiration if it does not. https://addons.thunderbird.net/en-US/thunderbird/addon/quotecolors/?src=ss

I saw that, but was under the impression it only affected how things were displayed locally and didn't alter the style of messages themselves. I probably misunderstood.

I've installed and tested quotecolors. It does control how messages are displayed when they are read. It does not affect the compose window nor the contents of the message that is sent. It only changes how it looks when you read it in the "sent" folder.

I've created an extension that adds a <style> element containing the desired blockquote CSS to the < head> element in the message document when I click a button on the compose window header. My replies are now acceptable looking in both GMail and Outlook. I've still got a couple things to figure out:

• Get rid of the button, and have my function run automatically once the compose window's document is ready
• Make the CSS to be inserted configurable (it's currently just a string literal in the extension's background.js).

Why are lists weirdly out-dented in this forum?

The extension I created to solve this problem is CustomCSS