Prospect.io allows you to add an opt-out link at the bottom of your emails to let the prospects unsubscribe from your mailing list. By default, an unsubscribe link is not included in the emails, but the account admins can turn it on.
To enable this option, navigate to the Settings > Outbound > Opt-out Link.
There are 3 options:
Disable opt-out links;
Insert opt-out links in all emails;
Let senders choose if they want to insert opt-out links in their emails.
If you choose the last option, your users can turn the opt-out link on or off from their Sending Address page.
The unsubscribed (opted-out) prospects are automatically added to your Exclusion list, and you cannot manually resubscribe them.
Note: preview emails don't contain actual opt-out links. Prospect.io generates a unique opt-out link for every prospect when you send a real email.