I do not have the time to code right now, but if I had the time to tweak Mozilla Thunderbird, this is what I would do:
- make more of a central cache for e-mails and e-mail content (perhaps instead of creating a bunch of msf files)
- integrate certain plugins (LookOut, QuickFolders)
- create a centrally managed version (maybe based on some sort of extended IMAP?) By this I mean what might be called a corporate version where everything is controlled on a central server.
- Create a single-tasking mode (maybe based on reading list from QuickFolders extension)
- Add a button to close and open folder pane
- Do not show preview pane until an e-mail is clicked (ie hide it every time you click a folder)
- Make sure connection can totally reset from within an e-mail draft without being trapped in a loop where you can no longer save draft and no longer send.
Fix the following bug (IMAP IDLE no longer works and has not worked for a while):
The related bugs (there are many) may say the problem is fixed but it is not. The issue boils down to the IDLE connection is closed right when the new mail message should arrive so Thunderbird does not say a new E-mail has arrived.