Hi @jscottcoatsworth,
Sorry, we didn’t get any email from you. Also, it is forbidden by WP community to share email address in public thread. As per WP T&C we have to solve everything within thread. However, you could use some image sharing online service to share screenshot with us . Here is a similar site https://imgbb.com/ you can use it to upload and share the link.
This plugin is dependent on php IMAP extension ( https://php.net/manual/en/book.imap.php ) to connect mailserver and process bounced email. From our experience , not most of the web hosting server has this extension installed or sometime web hosting company keep this extension disabled due to their security policy. Now, if PHP IMAP extension is not active in your web hosting than this plugin will not work.
Now, you can also verify that if PHP IMAP extension is enabled or not within your web hosting.
Also, if you know how to check browser console error, please check if there any console error during connection test.
Thanks