Actually Thunderbird is able to use Maildir instead of Mbox - you just have to enable it before creating your account. Image shows Thunderbird 78.X. This though is one of the newer options, so probably was not around when you used it.Time to tell that I don't use SeaMonkeys mail client - I'm using just the web browser. Claws Mail is the one I'm using. I've used Thunderbird years ago for a few months, but the concept of saving many mails in one file is to fragile - seen to many users with that format loosing their mail spool (and IMAP isn't an option - my private and commercial stuff is nothing I want / being allowed to lay around on servers out of my control). Claws Mail gives me MH. Save, usable by scripts, controllable.
bsduck: programs under BSD which do offer that view are Evolution and Kmail. Evolution is quite slow, and Kmail relies on Akonadi which never worked well for me and pulls tons of KDE dependencies in it as well.
No, thanks, I would really much like to have that view in Thunderbird, because I like Thunderbird as many other people as well, I'm using some addons as well and I don't know if these would work with other programs or the functionality is in them. Thunderbird wants to be an all purpose every day mailer, but not having that view in it really is a big shortcoming of it. People have been asking the developers to change that view since ages, but unfortunately it doesn't get the love here it deserves.



