A contact can have any of the following subscription statuses for emails and sms:
The contact has provided an email address or phone number and has specifically opted-in to receive marketing messages
The contact has provided an email address or phone number but has not agreed to receive marketing messages. Emails that are transactional (rather than marketing), such as those triggered by an abandoned cart or order placed, will be sent to non-subscribed contacts. SMS text messages will NOT be sent to non-subscribed contacts.
This means that the contact has specifically unsubscribed from receiving marketing messages. Campaigns and flow-triggered emails or sms will not be sent to these contacts.