There is no generic recipient-independent resubscribe link in this flow

For school administrators using GiveCampus Outreach. Controls can differ between the classic email editor and the newer Composer editor.

The resubscribe URL contains a signed token for a particular unsubscribe record and topic. Open Outreach → Reporting → Email Unsubscribes, locate the appropriate recipient and topic, and use the envelope action Send Resubscribe Link rather than copying one person's link to everyone. Sending the request does not itself re-enable mail.