In my company, a public administration, Thunderbird is installed on about 5,000 workstations and we really appreciate the software. However, we encounter difficulties with many employees who need to manage PEC backups in MBOX format.
Thunderbird has almost everything needed for this mode of use, it's just missing a dedicated graphical interface that guides the user with simple steps.
I am convinced that such a change would make Thunderbird even more complete and user-friendly.