Author: Mark Nelson
MDL-64017 message_email: task to send messages as a digest
http://git.moodle.org/gw?p=moodle.git;a=commit;h=168d782ff887cb7ced150a1220cf455780c67b06
http://github.com/moodle/moodle/commit/168d782ff887cb7ced150a1220cf455780c67b06
+ 3.7 en [emaildigestsubject,message_email]
+ 3.7 en [emaildigestunreadmessages,message_email]
+ 3.7 en [emaildigestviewallmessages,message_email]
+ 3.7 en [tasksendemail,message_email]