mail-abbrevs-mode

mail-abbrevs-mode is a variable defined in `mailabbrev.el'.
Its value is

nil

Documentation:
Non-nil if Mail-Abbrevs mode is enabled.
See the command `mail-abbrevs-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `mail-abbrevs-mode'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 20.3 of Emacs.