[FIX] mass_mailing: fix issue in _get_mailing_model
[FIX] mass_mailing: fix issue in _get_mailing_model

getattr crashes and in this case we probably meant to use hasattr as we
have a fallback behavior.

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo