Right-click a subfolder, Properties. Is the box 'When getting new messages...' checked, and if not, does checking it restore the indicator of new mail?

Hi.

I do not have a "When getting new messages" box.

On closer inspection I think the bold text indicating unread mail might be turning a very dark blue but it is so close to black as to be virtually indistinguishable.

The 'When getting...' box is not shown for Inbox folders, since they are checked by default. The setting applies to folders other than Inbox.

Are you using a dark theme? The folder name and unread number color can be defined with a userChrome.css:

treechildren::-moz-tree-cell-text(hasUnreadMessages-true)
{color: red !important;}

There is additional code for new vs. unread mail, but I find this sufficient.

Help/Troubleshooting, Profile Folder, Open Folder, close TB, create a new folder named chrome, create a new document in chrome with a text editor, name it userChrome.css, Save as type: All files *.*, copy in the above code, change the color as desired. Double-click toolkit.legacyUserProfileCustomizations.stylesheets to true in Options/General/Config. editor, restart TB.

A step in the right direction I think but the colour (red) now shows for boxes with unread mail. What I need is something to indicate NEW MAIL in the box

This is particularly important as I have dedicated boxes that receive copies of automated mail sent from my server to customers, customer orders and IPNs from PayPal.

Do you have any more suggestions please?

Try this:

/* Highlight Folders if subfolders have unread messages */
treechildren::-moz-tree-cell-text(subfoldersHaveUnreadMessages-true) {
  color: red !important;
}

/* Make Folders having Unread_Messages distinct from others */
treechildren::-moz-tree-cell-text(hasUnreadMessages-true) {
  color: green !important;
}

/* Change Folder Display to indicate New Message(s) arrived */
treechildren::-moz-tree-cell-text(folderNameCol, newMessages-true) {
  color: orange !important;
  font-weight: bold !important;
}

Brilliant. Thank you for the time and trouble to sort this out for me. Now have the folders as they were prior to update and learnt a lot about CSS.

Many thanks

That's ridiculous. An ordinary user shouldn't be having to fiddle with code to put right what the latest update broke. Prior to this update 78.5.0 the main menu words were legible (now mid grey on pale grey when I'm working elsewhere, almost invisible to older eyes), menus have lost all colour, the viewing pane has lost its - button to shrink the header to 1 line. And there's this perpetual annoying message demanding I purge deleted files and no way of saying not to continue nagging me. All retrograde steps and, being a mere user, I don't want to fiddle with code to repair the damage.

I found a way to tell which folders receive new mail. Whoever changed TB from 68 to 78 changed the color used to indicate new mail from light blue to dark navy (basically black). So, you can't easily see when the text of the folder name changes from black to dark navy which now indicates new mail.

So, I changed the color of all the folder icons to red or gray. Red if the folder has a message filter on it, gray if it doesn't (gray folders won't get new mail). Now when I Get Messages and new mail comes in to the folders with red folder icons, the folder icon changes from red to TB78's dark navy. So, a dark navy folder among the red (or gray) folders is easy to spot and I only look at those for new mail.