How does Mac Mail's "unsubscribe" feature work?

How does Mac Mail's "unsubscribe" feature work ?

By the unsubscribe feature, i mean the feature as per the screenshot attached.

Eg. Does it follow the unsubscribe link that was sent in the email, or does it just add the sender to a "junk" list ? If the latter how can we ensure non "newsletter" messages from this sender dont go to junk.

Im running Mac OS Big Sur, but ive also noticed a similar feature in recent versions of iOS.

Apple's Mail app looks for the list-unsubscribe header which contains the mailto: address to unsubscribe from a specific list. Not all senders include this in their emails which is why not all emails have the 'unsubscribe' link.

Mail then creates a simple email from your address and sends the 'unsubscribe' email for you. This is the same process as if you would send an email yourself to unsubscribe from that list.

The benefit to the email sender is that by using the unsubscribe link, you're less likely to mark the email as spam on your email service provider (which negatively impacts the sender's email reputation) or send a complaint to the government entity responsible for monitoring spam (in the US it's the FTC).