[wnevets]

I believe it uses a header the sender includes with the email

http://www.list-unsubscribe.com/

[9fb29947]

Cool. I doubt those intrusive marketing emails will ever include that header though.

[asddubs]

it's a neat feature for legit websites not wanting to end up on spam filters, though

[kpcyrd]

Also a cool way for a spammer to verify if somebody is receiving those mails.

[ascagnel_]

True, but that's a low- to no-value lede; you're not very likely to sell to someone that's actively trying to avoid you.

[jonknee]

Who cares if they are receiving them and never seeing them because they are blocked?

[detaro]

Someone who easily can send other mails to the now verified address from somewhere else?