I just selected the option “all e-mail folders” under the archiving scope in the account preferences and performed an archive operation - but still can’t find archive’s folder in the list of local folders. Can you please help me?
Ah and are the already archived e-mails now lost?
Is the option to display Local Folders selected in Menu > Tools > Settings > General > Show Local Folders?
I can’t find Menu > Tools > Settings > General > Show Local Folders.

I’m amazed at your response speed! Thanks and congratulations!
But I checked and the box you indicated to me is already flagged. I also tried to unflag and then flag it again and closing the application and restarting it, but nothing has changed.
I’m using Mac BookPro with OS X El Captain

Screenshot with errors.
The archive should appear under Local Folders.

As far as I know it won’t appear unless it actually has content. Were some messages already moved Stefano?
If you are using a Free License, only two email accounts will be active and only those two will show in the left side-bar.