I do not understand why that can be! Tried a lot ... e.g. I set my own domain, my default odoo domain, no domain, different aliases but I do only receive emails from  my odoo users.

All the other aliases e.g. for leads/chances are doing well with receiving from every email address and create a record.

I also tested it with a fresh new database and everything works fine here. the mail from every sender arrives in seconds.

But my actual database only receives emails from my odoo users.
Same alias-preferences for the vendor bill alias like in the fresh database.