Email Validate, if this is check it validates that an email address has been entered, unchecked it relies on your email provider to provide a message that there was no email address enter or the email address is not valid. You can test this by checking and clicking the submit button with the email field empty, you will receive a message.
The Llr, M and P are values that need to be entered in when you create your optin form within ConstantContact.
In the below example:
llr value = boyqjdlab
m value = 1111433437633
p value = oi
<form name="ccoptin" action="https://visitor.r20.constantcontact.com/d.jsp" target="_blank" method="post" style="margin-bottom:2;">
<input type="hidden" name="llr" value="boyqjdlab">
<input type="hidden" name="m" value="1111433437633">
<input type="hidden" name="p" value="oi">
Yours will be different to the examples I have given.