I thought I had the same problem, then discovered my own e-mail in my Junk folder…
I am just now checking this plugin out for the first time, and I am quite impressed so far! I do my homework before clicking, and here is where I was first quite impressed:
…it makes no modifications to site-wide .htaccess files. We will never be responsible for toasting your WordPress site because we introduce a bug and destroy your .htaccess. Too many plugins are hitting these file, we found, and it more-often-than-not breaks websites because the variables involved are too numerous to count. The last thing we want is a broken .htaccess party – the worst kind of party.
https://www.icontrolwp.com/2014/05/wordpress-security-wordpress-simple-firewall-plugin-part-1-why/?utm_source=in-plugin&utm_medium=plugin-readme&utm_content=www.ads-software.com&utm_campaign=WordPress%20Simple%20Firewall%20Plugin
And, I even had to tell it to ignore me so *I* could write to that file! That, I say, is a bit of security.