Hello,

I've found this information on this forum :

The following heuristics are used, in this order:
 * if the message replies to an existing thread by having a Message-Id that matches an existing mail_message.message_id, we take the original message model/thread_id pair and ignore custom_value as no creation will take place
* if the message replies to an existing thread by having In-Reply-To or References matching odoo model/thread_id Message-Id and if this thread has messages without message_id, take this model/thread_id pair and ignore custom_value as no creation will take place (6.1 compatibility)
* look for a mail.alias entry matching the message recipients and use the corresponding model, thread_id, custom_values and user_id. This could lead to a thread update or creation depending on the alias * fallback on provided ``model``, ``thread_id`` and ``custom_values`` 
* raise an exception as no route has been found

I've configured my incoming emails without alias (for now) and now here is how it works :

When I send an email from Odoo client interface and the client answer to this email. I received the answer in Odoo client interface. That's fine !

 When this client send an email, it doesn't go to the odoo client defined. I can see this error in the log :

ValueError: No possible route found for incoming message from Lemaire dupont <lemairedupont@icloud.com> to Ludovic <ludovic@gmail.com> (Message-Id <139A76A5-91A2-4F1C-A144-EE3F371BC567@gmail.com>:). Create an appropriate mail.alias or force the destination model.

How can I solve this ?

Also, for all other emails incoming which are not related to a know client, is it possible to receive them in my dashboard inbox ?

Thanks in advance for you help.

Ludovic