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=33a4c4a3b9c3a8674229ec643bf91acd23175ea3
http://github.com/moodle/moodle/commit/33a4c4a3b9c3a8674229ec643bf91acd23175ea3
+ 4.0 en [messageundeliveredbynotificationsettings,core_error]