Sendy Mod: Block disposable emails

Hello,

Few of us asked for this small feature (https://sendy.co/forum/discussion/comment/5408 and https://sendy.co/forum/discussion/850/block-disposable-temporary-e-mail-address/p1), I do not want disposable emails to subscribe in my lists, also I want to validate that the domain subscribing has a valid MX record so we are sure they do not subscribe with non existent domains, such as asdadadasdasdefer.com.

This mod was really easy to do, I've tested for few days works like charm.

Just replace the file content /sendy/includes/helpers/EmailAddressValidator.php

for https://gist.githubusercontent.com/neo22s/502dd133fa809fc6a8fd/raw/d7d0e86491751462083b70eb6df59ce8ab654f3e/EmailAddressValidator.php