To be more specific, always open a folder in a new tab, and open in new tab when new mail arrives.

https://support.mozilla.org/en-US/kb/message-tabs https://support.mozilla.org/en-US/kb/keyboard-shortcuts

Cannot locate anything to auto open folders receiving new mail in new tabs. But you would end up with loads of tabs.

Certain things are just manually done.

If you are looking for a simple method of viewing only a short list of folders with new unread emails: 'Menu icon' > 'Folders' > 'Unread'

Or within a folder to shrink list You could use the 'Quick Filter Bar' unread icon

OR 'Menu icon' > 'View' > 'Messages' > 'Unread' or 'Menu icon' > 'View' > 'Messages' > 'Custom Views' (you can edit those auto created or create your own) You can also add a 'Mail Views' button to the Mail Toolbar.

Thank you for the helpful tips, as they do work. However, what I am looking for is the same default actions as they were in Eudora, i.e., clicking on a folder opens in in a new tab in the foreground; and upon receipt of new email in a folder, the folder would automatically open in a new tab in the foreground.

I agree 100% with pwolotsky. This was a core, very useful function in Eudora. It prevented losing track of any new mail into a folder that I'd already reviewed but not marked everything as read because it was important that I review the Subject lines, but not important enough to deal with the messages.

In Eudora my email filtered into folders, and all of the folders opened with the associated mail. I could deal with those folders or not, but it meant I didn't have to dig through the folder tree for mail, but I could deal with it as part of the associated folder. For folders I didn't care about I could just close them. Mail was grouped, so I could deal with mail in context of the related emails. I'd hate to hear that function was intentionally removed!

I'm completely aware that it could open many folders - that's exactly the point. "Certain things are just manually done" is a horrible answer from a design perspective. I could manually move all of the email into folder as I desired, but instead there's the filter function which does that for me. Because there's a better way.

This concern could easily be remedied with a filter action of "open folder as tab." without impacted overall usage for all users. Those that wanted it could add it, those that did not desire that behavior could just not use that filter option.