Email Valditations

There's also this one too:
I think these should mainly be used if you're sending emails through your own delivery servers, so that you can filter out non-existent emails and have a chance in plus to keep your delivery server ips clean.
On another hand you can also use them as a prefilter when sending with amazon(or any 3rd party service), so that you keep your sending reputation clean.
Thanks for the answer.

Okay, so pretty much it should be used for troublesome customers ;)? :D
Is there a way to add it to customer groups?