Did you know that the latest versions of FormBuilder support extension modules? The one we just released is called "SMTP Controls" and it allows FormBuilder to send it's email through any standard SMTP service such as Mandrill or SendGrid.
This gives you much more flexibility over how email is handled without having to depend on potentially flaky local server based email systems. Some SMTP services also offer extensive tracking and reporting on email deliverability which can be a great aid in managing your website's communication effectively.
Read more and get it here:
http://www.warkensoft.com/wordpress/formbuilder/formbuilder-smtp/