If you have the global setting turned on to include an Unsubscribe Link in your automated emails, which will fall under any emails sent from a Sequence or the Bulk Email feature, there may come a time in which you will want to know who has unsubscribed.
Uptics will let you know in the notification bell when a contact record has unsubscribed, as well as point this out on the Signals tab in your Sales Inbox, but if you'd like to filter for these leads you can do so on your Contacts List Pages.
To do so, simply click the +Filter button near the top middle of your screen, search for the property Email Subscription, and choose your conditions. Choosing 'Unsubscribed', as shown below, will query the list of records that have unsubscribed.
Because the unsubscribe link is an opt-out, there is no way to re-subscribe a record to start sending them more emails.
You may find this property useful to save as a SmartList and use it as an auto-unenrollment trigger in your sequences that also contain manual outreach via phone call, LinkedIn, and/or outbound SMS messages if you wish to apply their unsubscribe as an opt-out to all forms of communication.