If you've submitted the manual resubscribe confirmation email to the contact, and they're either not receiving it or they can't get the link to work due to a connectivity error, then there's still a couple options available.
The easiest method for a contact to resubscribe to you would be for them to go through one of your sign up forms.
If they’re unable to get signed back up through a sign up form or through the resub email, you can request our Review team do a manual override of the unsubscription. You’ll need to get an email directly from the contact explicitly stating they want to be resubscribed. Then you’ll need to call into the Review team, and follow their processes from there.
Since there are a number of legal and Compliance-related elements to unsubscribing and resubscribing, we have to make sure one of these three processes is followed.