One of the improvements Apple made to the Mail app in iOS 10 is the introduction of an Unsubscribe link for emails that obviously come from mailing lists that presumably the app scans the message for any mention of “unsubscribe.”
The recipient just taps the blue shortcut link at the top of the email and then confirms their choice on the next pop-up. Mail will then send a message from the recipient to the sender that they are no longer interested in receiving these emails in the future (see below).
As for us marketers.. this may not (and most likely does not) sync with any email marketing software to automatically unsubscribe the recipient from a database... this is where it may become tricky to manually manage unsubscribes....
Your best action would be to check with your email service provider to see how these unsubscribe requests are monitored in order to comply with them and if its not automatic... you will need to put into place a system to make sure the recipients are unsubscribed to comply with the CAN-SPAM regulations.
Although unsubscribes are typically seen as a bad thing... at the end of the day, why would you want to send emails to people who don’t want to hear from you?
They could very well mark you as spam instead if they don’t find a way to opt-out, and this will hurt your overall deliverability in the future.