We should update our message list to be threaded by default.
This change should only be available for new profiles, therefore a migration is needed to change this pref without affecting existing profiles or users that changed that pref already.

This is more complicated than expected.
Anyone has any idea where these default sorting options might be handled?

This would be this set of prefs to set the defaults: https://searchfox.org/comm-central/rev/91923108c54cd5e574fbaeed2b6af0cbeee37d37/mailnews/mailnews.js#79-104

I agree with threaded, but personally I think the date descending might be more controversial. I know there's been lots of comments in the past for the default to be the other, but I think you'll get complaints the other way with this change (personally I prefer ascending). It might be worth adding telemetry to see what people actually use within their folders.

Something you are hopefully aware of - I believe existing users with accounts set up will have already visited folders with the existing value of the preference. Changing the preference "behind the scenes" will potentially keep the folder settings the same for those existing folders, but will change it for new folders. Given the default is hidden away in about:config, you might need to consider how the default is changed - should it only be for new profiles?

Additionally I think "Apply columns to" ... "Folder and its children" probably doesn't help here, firstly it is also hidden away and secondly I don't think it sets these preferences (it'd maybe nice to have "Apply columns to all accounts, folders and for any new folders").

(In reply to Mark Banner (:standard8) (afk until 18 Apr) from comment #2)

This would be this set of prefs to set the defaults: https://searchfox.org/comm-central/rev/91923108c54cd5e574fbaeed2b6af0cbeee37d37/mailnews/mailnews.js#79-104

Thank you so much!

I agree with threaded, but personally I think the date descending might be more controversial. I know there's been lots of comments in the past for the default to be the other, but I think you'll get complaints the other way with this change (personally I prefer ascending). It might be worth adding telemetry to see what people actually use within their folders.

Fair point.
I will only enable threaded by default and don't touch the order.

Something you are hopefully aware of - I believe existing users with accounts set up will have already visited folders with the existing value of the preference. Changing the preference "behind the scenes" will potentially keep the folder settings the same for those existing folders, but will change it for new folders. Given the default is hidden away in about:config, you might need to consider how the default is changed - should it only be for new profiles?

Yes, I'm aware of that, thanks for the heads up.
I'll make sure to add a migration to only update that pref on new profiles.

I'll make sure to add a migration to only update that pref on new profiles.

Actually, that's not necessary.
If the user already edited that pref it won't be overwritten.
If the user didn't touch that pref, newly created folders will be threaded by default, which I think it's acceptable and a sane default.

The data ordering is more "visually disrupting", so we can avoid touching that, but the threaded can be easily toggled if the user doesn't like it.

(In reply to Alessandro Castellani [:aleca] from comment #0)

We should update our message list to be threaded by default.

Can you please give a reason for this? IMHO, threaded view is more for geeks, not the common users who will make up the largest part of the user community.

It was before your time, but the introduction of the Correspondents column and a forceful migration caused a huge backlash (read first line of referenced bug) and the migration had to be removed again (bug 1268325).

If the user didn't touch that pref, newly created folders will be threaded by default ...

That will cause a mixup and huge user disappointment. Changing well-established preference defaults is really a "no go zone". If you later decide to change it back, you will affect all the users who had changed it in the first place since their value will become the new default and hence not be stored any more.

As a personal off-topic remark: Why don't you fix some still-open regressions in version 91 before they hit 102 before embarking on new projects? Like adding attachments is still not fully working (bug 1732903).

(In reply to newsfan from comment #6)

As a personal off-topic remark: Why don't you fix some still-open regressions in version 91 before they hit 102 before embarking on new projects? Like adding attachments is still not fully working (bug 1732903).

You are correct, it is off topic and therefore not relevant to this bug report. Each issue should pass or fail, move forward or not, on its own merits.

(In reply to Alessandro Castellani [:aleca] from comment #0)

We should update our message list to be threaded by default.

Can you please give a reason for this? IMHO, threaded view is more for geeks, not the common users who will make up the largest part of the user community.

I've always been surprised it is not the default. However, whether or not one population is larger than the other, I don't see how geek has a different need than the common user in this area. Please explain.

If the user didn't touch that pref, newly created folders will be threaded by default ...

That will cause a mixup and huge user disappointment. Changing well-established preference defaults is really a "no go zone". If you later decide to change it back, you will affect all the users who had changed it in the first place since their value will become the new default and hence not be stored any more.

This approach ignores the possibliity that a "well-established" preference perhaps didn't even consider making a differnt default at the time the functionality was introducted, or that conditions or user patterns have changed in ten or twenty years.

But your observation that telemetry data might help is a good one. However that means examining multiple folders, not a centralized preference, no?

Pushed by alessandro@thunderbird.net:
https://hg.mozilla.org/comm-central/rev/12c95cd9deb6
Make new folders Threaded by default. r=mkmelin

That was a pleasant surprise when testing the 101.0b1 candidate on Windows 10.

As a volunteer on SUMO, I have seen numerous complaints on the new default. Most users prefer unthreaded. And there is no easy way for users to undo what you did. The config editor value of mailnews.default_view_flags being set to zero doesn't work. Please revisit why you felt that this long-standing default of unthreaded needed to be changed. Thank you.

For all the users that want unthreaded by default, we had for many years the same amount of users that prefer threaded by default.
Threaded view is the default in every email client, only Thunderbird was the outsider and new users (new to TB) were confused.
It's a personal preference and in this very own case it doesn't exist a clear right or wrong solution. Different users have different needs and we decided to do threaded because is an extremely common default to keep things more organized.

Setting pref("mailnews.default_view_flags", 0); should work for NEW folders. If a folder is already present, simply clicking on the thread button will make the whole folder unthreaded.
If these things don't work, please open a bug.

Thank you for the clarification. I will update my response to some users on the topic. The complaint was from users who upgrade to 102 and have hundreds of folders to manually change. I guess changing defaults will always cause conflict. Again, thanks for explaining.

Bugzilla is not a discussion forum, especially for closed bugs.
You can use one of our many mailing list to discuss this.

(In reply to Alessandro Castellani [:aleca] (PTO Dec 22 - Jan 9) from comment #12)

Setting pref("mailnews.default_view_flags", 0); should work for NEW folders. If a folder is already present, simply clicking on the thread button will make the whole folder unthreaded.
If these things don't work, please open a bug.

How exactly does one set pref("mailnews.default_view_flags", 0);? Plus how is a non-dev user supposed to figure that out I wonder?

(In reply to Michael Bauer from comment #16)

How exactly does one set pref("mailnews.default_view_flags", 0);?

How to make new folders in Thunderbird default to unthreaded

Due to popular demand (and as the pref is pretty hard to find and use), I've created a new section titled Changing default threading mode with detailed steps in the Message threading in Thunderbird article.

Note that changing the hidden pref mailnews.default_view_flags to 0 (unthreaded) will only apply for new folders created after the change. For existing folders, there are other methods documented in the article.

Plus how is a non-dev user supposed to figure that out I wonder?

As of today, they can find information in the support article, but I'm still in favor of exposing this pref in the settings UI.

(In reply to Thomas D. (:thomas8) from comment #17)

Thanks for the links

As of today, they can find information in the support article, but I'm still in favor of exposing this pref in the settings UI.

As am I, it's an untenable position IMO to make users trawl through the advanced settings for something that used to be the default setting.