If you prefer unthreaded folders, this may help: You need to highlight each folder and click View>sort by>unthreaded. If this applies to just a few folders, just repeat the process as necessary. If you have many folders or plan to add many new folders, you may wish a different approach, below: (If you do not see 'View' in menu bar, press Alt key to display menu bar)

More info: To change default for *new* folders, In config editor, you can change default that applies to NEW folders you set up: mailnews.default_view_flags 0=unthreaded

Config editor is available at Tools>settings>general and scroll to bottom right. No CSS customizing is needed for this one feature.

Thanks for your response but no, what I am wanting is the 'header' of all the nested messages to become bold when a new message is inserted within the thread of that 'header'.

See https://support.mozilla.org/en-US/questions/1442668#answer-1642934

Thanks sfhowes. But the point of my post was to have this behavior as an integrated 'feature' of Thunderbird itself. Not something people have to go off and 'code/script'.

Well, this is a support forum, helping users work with Thunderbird as it exists. If you have ideas for improvement, please consider going to connect.mozilla.org and post your idea there. Then, others will see it and add their comments. Thank you.

"Well, this is a support forum, helping users work with Thunderbird as it exists. If you have ideas for improvement,"

Ok, thanks. Although my original post was not so much an idea, but an inquiry.(It was implied as it seemed obvious, even though I didn't ask explicitly).

That's because Thunderbirds changes to nesting new and existing Emails is a good idea in itself, which I like.

But in the process of making things better, they left out what was good before - highlighting at a glance, in bold, for new Emails. Making the new changes more like a tradeoff rather than an improvement. End user chooses which one they want.

It seemed so obvious to me to have both old and new behavior that it must mean I'm missing something.

I.E. I'm probably not finding the place in settings in which I can enable the old behavior and also keep the new. (hence my inquiry here).

So judging by all the responses, that is not the case(a settings matter) and as you mentioned could be addressed elsewhere.

I agree the display that the css provides should be a built-in feature. So you have two choices: request an enhancement on Bugzilla, which might take months or years or...never, to appear in a release, or spend two minutes to copy the css into a file and place it in a subfolder of the profile. The second choice is far easier than downgrading to an older version that has the old behaviour, but has reached end-of-life.

I have a third choice - And one of the main reasons for putting time on this subject to begin with.

It's about this sort of feature for everyone - So that the program is more accessible to more people - because they don't have to learn, 'fidget' and maintain a 'hack'.

It's an Email program for an end user/s.

And as David pointed out, there is the 'idea' part of Mozilla, that takes such postings on suggestions. It's been done.

I have a third choice - And one of the main reasons for putting time on this subject to begin with. It's about this sort of feature for everyone - So that the program is more accessible to more people - because they don't have to learn, 'fidget' and maintain a 'hack'. It's an Email program for an end user/s. And as David pointed out, there is the 'idea' part of Mozilla, that takes such postings on suggestions. It's been done.

Did you miss the point raised about this being support and that there is an ideas/feedback forum. just for future reference there is a link also on the Thunderbird help menu 5 items below the link to this forum.

I am locking this topic as there is no longer a support issue here. Just misdirected feedback. Please expend your efforts where it might do some good. This is a peer forum. You are only dealing with fellow users.

If you want your feedback heard place it appropriately.