This follows [commit 1], which introduced a way to separately reorder columns on mobile and desktop. This commit replaces the custom mobile order classes with the Bootstrap `.order-x` classes. It also ensures those orders are not used for mass mailing in case the editor composes their email on a small window. The reorder would indeed not have any effect for the end users in such a case. [commit 1]: https://github.com/odoo/odoo/commit/710d000f1872fd99b41d52ec3d6923756bba7cba task-3576046 closes odoo/odoo#140362 Signed-off-by: Arthur Detroux (ard) <ard@odoo.com>