The instructions about +tag addresses state:
“Every incoming email address also receives mail for +tag addresses. If your email address is email@example.com, you’ll also automatically get mail sent to firstname.lastname@example.org. Use this as a fast way to segment incoming mail for your own filtering rules without having to create aliases in this control panel.”
When I send a test email to test+me@myMailServer.com, the email gets rejected, and bounces back.