Purpose of this commit is to have recipients of an incoming email being
present only once in recipients / to. Indeed there is no need to have
duplicate entries, for example if Delivered-To is set with same content
of To.
Followup of 7b79045fab .
LINKS
Task 2076366 (send now)
Task 2067873 (template access)
PR #37298
PR odoo/enterprise#5750