Purpose of this commit is to add some mass mailing tests in test mail full (with all community mailing capabilities installed). In this commit we notably tests unsubscribe and view URLs computation in sent emails, as well as the invisible preview block for email clients. Task ID-2239327 Task ID-2239327 PR #49886 Related: odoo/enterprise#10091 Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>