How many times have you received buckets of emails from the same publisher and finally decided to unsubscribe only to fine that the publisher has added some friction like a subscription configuration form or even prompting you for your email address? It happens to me from time to time.I used to think that the publisher was lazy or simply not taking the time to customize the unsubscribe link. But as I looked closer at the email other elements like my name in the header and to fields and sometimes in the footer of the email. So it’s clear to me that they are already doing some of the required work and adding a GUID to the unsubscribe would be trivial. The reality is that the publisher is adding friction in the hopes that I/we/you abandon the task at hand.Which leads me to a word of warning for publishers of this type. Make it easy for me to unsubscribe or I will mark you as spam. If enough of my peers mark you as spam the filters will get you and it will cost you a lot more to clean that up than the fraction of a basis point that you got from my email.