“Every incoming email address also receives mail for +tag addresses. If your email address is you@yourdomain.com, you’ll also automatically get mail sent to you+anythinghere@yourdomain.com. 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.
Yes. test+me@myMailServer.com will be delivered to the inbox test … and then assuming that you have set filters up in Roundcube it will be handled as specified with the filter.