formnovalidate

This atrribute allows the submission of a form even if it contains  invalid fields. For example:  a form that has an <input type="email"> field or a field required and which are not filled. 

In general, such forms have two submit buttons, one with the formnovalidate attribute set to a non null value and one without.

Typical use (online example at JSBin):

<form action="form.php">

   <fieldset>

     <legend>Example of formnovalidate attribute</legend>

     <label for="email">E-mail:</label>

     <input type="email" name="email" id="email"/><br>

     <input type="submit" value="Submit" /><br>

     <input type="submit"

            formnovalidate 

            value="Submit without validation" />

</fieldset>

</form>