Capabilities/block/quickmail:cansend
From MoodleDocs
If a user has this capability, then s/he can see the Quickmail block in the course and use it to send emails to other users in the same course.
Note: You are currently viewing documentation for Moodle 2.4. Up-to-date documentation for the latest stable version of Moodle may be available here: Capabilities/block/quickmail:cansend.
