Mass Mailing campain cannot use Mail Templates anymore (the user now
has to duplicate a previous Mass Mailing if he wants to start a new
one with a mail body which looks like the old one).
So this menu became useless and confused the users. Mail Templates are
a technical feature which is used by other module to send automatic
emails and these can be edited through debug mode in the Settings app.
Resolve#14148.
qsm-odoo
dff12736db