Bug
===
Since 2d359b909b we moved the mailing
list feature of the <mail.channel> in a different model, <mail.group>.
During this split, some SMTP headers have been forgotten.
Task-2721009
closes odoo/odoo#81887
X-original-commit: daf9c0300fb042891c019e4f2a8c5395de388e1c
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>