I can see that there are 2 relevant directories which are used by Evolution 3.4.3 to store mails:
My Inbox vfolder has 7500 mails, has claimed in Evolution.
And the Trash is supposed to be emptied at the exit.
In the first directory there is a huge (1.2 GB) "Inbox" text file which has 6000 entries
(cat ~/.local/share/evolution/mail/local_mbox/Inbox | grep 'From ' | wc -l).
Surprisingly the last entry is dated 06/2011. I guess that more recent mails are stored elsewhere (but where ?).
Also, I can see that there are still old mails which are supposed to have been deleted in Evolution (Folder>Expunge).
How Evolution process with mail storage ?
Is-it possible to remove deleted mails from the Inbox file to gain storage (there is a "compact inbox" option in Thunderbird which does this) ?
Thanks for your help