You are using an outdated commercial version of the plugin. Update to the latest version to correct that problem and keep it compatible with the latest PHP versions.
Could you clarify what you mean by ‘Past due actions’? If you can share a screenshot or describe where they are listed, I can better understand what’s triggering them.
We’ve added a new Email Diagnostics feature to the plugin to help identify the delivery issues you’re seeing. Please try using this tool to gather more details. Additionally, enabling an email log system can provide a clear history of what is happening with your outgoing messages.
This issue may be caused by a conflict with a caching plugin or server feature that is causing the nonce to become invalid. If a nonce is served from a recent cache, it may work temporarily; however, once the cache expires or becomes stale, the system will attempt to verify an expired nonce, resulting in an error.
If you prefer to keep your current cache settings, you can deactivate the following option in the Contact Form Email plugin to prevent this conflict:
