Setup mail catcher or real email In config.php set up some email diverting rules $CFG->divertallemailsto = 'your@email.com'; $CFG->divertallemailsexcept = 'exception@email.com,.*example.com'; Confirm these are shown as normal settings here: YOUR_MOODLE_URL/admin/settings.php?section=outgoingmailconfig Delete them from config.php and then set them manually from the admin page. Test sending various emails using YOUR_MOODLE_URL/admin/testoutgoingmailconf.php and confirm the emails are diverted/not diverted as follows. Recipient Email diverted? s1@hello.com Yes exception@hello.com Yes exception@email.com No s1@example.com No Note: Diverted emails will have the word " DIVERTED " on their subject Test that diversion rules also work by separating them with line breaks instead of commas.