Author: Eloy Lafuente (stronk7)
MDL-68070 messaging: Amend lang string to be clearer for any user.
Credit goes to Helen Foster for the improvement, thanks!
http://git.moodle.org/gw?p=moodle.git;a=commit;h=2020abe0d86891f63a1af0970fdd7d8366eaa60c
http://github.com/moodle/moodle/commit/2020abe0d86891f63a1af0970fdd7d8366eaa60c
+ 3.8 en [messageundeliveredbynotificationsettings,core_error]