I have the simplest Email form from EE docs: https://ellislab.com/expressionengine/user-guide/add-ons/email/contact_form.html
Upon 'Submit' I get returned to the homepage of our site. Also, there are no Error/Success messages upon form submission.
We are able to send Emails through Tools > Communication.
As a test, we installed Solspaces Freeform (Free version), the same thing happens.
We've used the Email module many times on other sites without any trouble. This time around, we're on a different server and not sure if we're missing something on our config.
We had a static index.html on our www folder. Removing that file, fixed the issue.