Quickmail block
From MoodleDocs
The quickmail block adds a link to a tool that has a checkbox list of all students in the course, and a mail composition text area. You can check the students you like, and email those and only those. This enhances the existing communications systems of messaging (one user) and subcribed forums (all subscribers) by allowing teachers to select a specific subset of students. It was developed by Michael Penney's team at Humboldt.
