Here’s more information. Since there are thousands of others using the plugin without any issue, it is most likely due to one of the following reasons:
1) The “user” is not a contributor. Please double-check. Some admins mistakenly think an user has “Contributor” status, but they may be an Author or Editor.
2) Your server / hosting provider configuration is blocking emails. The plugin relies on the default WP mailing functionality. To resolve this on some hosting providers, some people install a SMTP handler for sending your emails such as Easy WP SMTP and it works like a charm combined with this plugin.
3) Your email service provider (gmail, yahoo, etc) is either sending the emails to spam (check the folder).
4) You have a conflicting plugin – most likely one that messes with your mail settings.
Please verify. Also, we’d appreciate it if you updated your 1-star review after determining the actual reason for the issue.
Thank you.