Before this commit, the mail scheduler in event bypassed the email_from field
in the selected template, implementing instead its own logic.
With this commit, the scheduler respects the `email_from` field from the mail
template, and only implements its own logic if that field is not set.
Task-3092425
closesodoo/odoo#111462
X-original-commit: ef503e62480c774e8a0d193666cc4cce5ab90282
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>