Open the advanced config editor by going to:
Settings > General > Config Editor
Sort by Date
Check for
mailnews.default_sort_type
and make sure it is
18
Note
17 = None
18 = Date
19 = Subject
20 = Author
21 = ID (Order Received)
22 = Thread
23 = Priority
24 = Status
25 = Size
26 = Flagged
27 = Unread
28 = Recipient
29 = Location
30 = Label
31 = Junk Status
32 = Attachments
33 = Account
34 = Custom
35 = Received
Change from Ascending to Descending
Change
mailnews.default_sort_order
from
1
(ascending) to
2
(descending).
Note
1 = Ascending
2 = Descending
Enable Threaded View
Change
mailnews.default_view_flags
from
0
(unthreaded) to
1
(threaded).
Save the settings and restart Thunderbird!