I don't get much spam, so I don't remember the last time I reported it, but IIRC when you do it on Gmail, it shows something to the effect of "thanks for the re

I don't get much spam, so I don't remember the last time I reported it, but IIRC when you do it on Gmail, it shows something to the effect of "thanks for the report, we'll try to unsubscribe you". I reckon they might be using this: https://www.rfc-editor.org/rfc/rfc8058 https://www.rfc-editor.org/rfc/rfc8058 This is pure speculation since I have no visibility into their inner workings, but it might just be possible that they would send a POST request on your behalf, at least to domains on some sort of a pre-approved list.