It's a good idea to test your form to ensure it works properly before making it publicly available. That way you can catch errors like this one!
If you submit your form and you get this error:
Your form could not be submitted for the following reason(s):
Failed to send an email to "firstname.lastname@example.org"
First, make sure you are using the latest version of Web Form Builder. Log in to the My Products section of your CoffeeCup account and download/install the most recent version.
Next, open your form and go to the Settings > Email Notices tab. In the Notification message area, ensure that a valid email address is in the "From" field. Save your form and re-upload all of your files.
In Mac OS X:
That should solve the problem!
Note: Some hosting providers will only process notification emails if you're using an email address they provide. If you're unsure of what this email address is, contact your web hosting provider.