Update: There appears to be a conflict between the new WordPress update and the plugin. To temporarily fix the issue on my sites I had to edit the FROM field in the MESSAGES for each form to: [your-name] <[your-email]> (alter the field name to match your form fields). If there is any other information or customization in that field the form would not work and I received the ‘FAILURE TO SEND’ message.
There appears to be an issue with the plugin. I was having the same error and found many others having it as well. Can’t find how to contact the developer for support. Any luck fixing it on your end? All my websites that use it are having issues.
I have this plugin that has suddenly stopped working as well. The form captures info to Contact Form DB but stopped sending emails without any changes to any settings. It’s not the email host. Possibly the form redirect or the plugin itself. Looking for any insights others may have.