Still getting erros on sending forms

I had two sites using the CoffeeCup Website Form Builder and both having trouble with their forms. When someone would try and submit the form, they would get the error:

Your form could not be submitted for the following reason(s):

Failed to send an email to “[email protected]”.

After much searching I found your plugin. It seems to have worked perfectly on one site, but the other site is still showing this error. Test emails from the plugin work fine; however when you try to submit the form, you get the above error.

The owner of the form, gets the form sent to them anyway, but the person submitting the form does not get their confirmation and since they see this error, they keep trying to submit the form multiple times.

Any ideas?

The page I need help with: [log in to see the link]