If you do not have any unread messages in your inbox, it won't import anyting as it will not import any of the existing messages having read flag true.

Try to send new message to your email address and try to fetch form Odoo or let be fetch automatically. 

Hi Mantavya

I sent messages to that mailbox but that messages did not come through. It s really weird. Do you see something else, a parameter...?

Thank you for your help

Sylvain