This is easier to test with the Moodle Docker container, which already has outgoing mail configured & Mailhog set up to collect the messages Configure multilang site full name Log in as admin Navigate to Site administration > Front page > Front page settings in Site administration Set Full site name to the following: <span class="multilang" lang="en">Moodle (EN)</span><span class="multilang" lang="de">Moodle (DE)</span> Navigate to Plugins > Filters > Manage filters in Site administration Set Multi-Language Content to On & Apply to to Content and headings Perform sanity check by visiting Site home and confirming the site heading shows "Moodle (EN)" and not "Moodle (DE)" Send test email Navigate to Server > Email > Outgoing mail configuration in Site administration Click on Test outgoing mail configuration In the field To email address enter: foo@example.com Press Send a test message Confirm that the e-mail message received has the subject: "Moodle (EN): test message"