In this commit we correctly use mailing variable inside a loop on self to enable multi-mode on convert_links method. We also update link_tracker shortening methods docstrings. We add some explanation, notably about parameters. A variable is fixed to better indicate parameter content (html -> content). closes odoo/odoo#55452 X-original-commit: 3e1633d5b3590ec5657b851c21cbae059944d964 Related: odoo/enterprise#12218 Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>