[Improvement] Local mbox should exploit the read/unread flag

[benintech]

I am using Thunderbird as a POP3 mail client.

I wanted to use Mailnag (and its Gnome's extension) to have a visual indicator of the number of unread messages of my Inbox (in mbox format).

It works (kind of), but it seems it uses its own indicators as to determine if a mail is unread. E.g., when I read a mail in Thunderbird, Mailnag still considers it as unread.

Yet, there is an indicator in the mbox file for each mail (X-Mozilla-Status, 0000 if unread, and 0001 if read). It seems Mailnag does not use it.