For student and staff support, it is sometimes useful to have a log of emails successfully sent out (at least, handed off to the smtp server without an error).

E.g. If a student complains they weren't notified of the assignment being graded, the log can be reviewed to see if the email was sent.

There are three approaches to logging that I can think of, all modifying email_to_user():

1. Add a new \core\event\email_sent event, to complement \core\event\email_failed in lib/moodlelib.php
   • Seems like the best use of the Moodle APIs.
   • However, built-in reporting tools don't seem easy to query.
   • Would probably be coded to only record the metadata (from/to/subject/date).
2. BCC all sent emails to an admin email account, via a setting like $CFG->bccmails
   • Creates an archive of the entire email, including the body - which could be good or bad, depending on one's requirements.
   • Requires an email account suitable for high-volume traffic.
3. Log all sent emails to a log file on the server (my current hack).
   • Not accessible from Moodle interface.
   • Easy to grep if one has CLI access.

Is this worth including? Which approach would be best?