Moodle eMail Test
The Moodle eMailTest plugin is a tool that enables administrators to easily test Moodle's mail system. A trace of the SMTP dialogue will be displayed if the email message cannot be sent for any reason. Version 3.x+ comes with a new diagnostic feature that helps you narrow down the issue and offers potential solutions. This feature makes it easier than ever to identify and resolve any problems with your email system.
Please note that once you’ve sent a test email, you’ll need to check your inbox to confirm that the message was delivered successfully. While this plugin won’t do that for you, it will provide troubleshooting suggestions if the email doesn’t make it to your inbox.