[AdamN]

I don't unsubsubscribe unless I explicitly subscribed in the past. If I did not subscribe in the first place then it's spam (exception for small businesses who may not know better in which case I'll delete or unsubscribe).

[sam_lowry_]

There are unsubscribe headers that are used by mail user agents like mutt to unsubscribe from mailing list managers like mailman.

These are "scanner-proof" so far but support in clients like Outlook or Gmail is non-existent.

[chuckadams]

Gmail not only understands the List-Unsubscribe header, it requires it for bulk deliverability.

[kstrauser]

I'll try unsubscribing once if it looks like a legitimate org, like someone I actually did business with but didn't expect them to email me. After that, it's going to the junk box to train the server what spam looks like.