There is a menu bar at top of message list and one of the entries is 'Date'. If you click it, the sort order reverses, letting you select to show new messages at top or bottom.

Thanks for the reply David.

I do have the list sorted by date with new messages coming in at the bottom. The problem is the list doesn't automatically scroll up to display the new unread message at the bottom of the list, it is hidden under the window that's just below the list of emails, so I have to scroll up one line so I can see it. (This is when new emails come in with TB minimized)

Well, scrolling up is something most people would not want, so my suggestion, to ensure you see new messages, is to set the sort to descending.

Understood,thanks.

I don't know why most people would not want the messages to automatically scroll up when a new message comes in (when sorted ascending) so it can been seen while TB is minimized, I certainly would. :-)

I would suggest Mozilla adds an option to allow that to happen, that would be great. In the meantime if it annoys me enough as you said I can always reverse the sort order so new messages come in at the top.

Thanks again.

Sorry, I worded that awkwardly. A clearer wording for that first paragraph would be:

I don't know why most people would not want messages to automatically scroll up when a new message comes in when TB is minimized (when sorted ascending), and then when you restore TB the new email can been seen without having to scroll down, I certainly would. :-)