I insert the sumple web form into edtor, like this

<form method="post" >
<input name="listid" value="6" type="hidden">
Email:
<input maxlength="80" size="20" name="optin_email" type="text">
<input value="Submit" type="submit">
</form>

Editor remove all <form> and <input> fields.

But I need this form on my page...

Could someone please help me how to configure Editor not removing my web form .