Details
If you have contacts that have been Auto-Deactivated, this would be because these contacts have permanently bounced. The system will automatically deactivate these contacts to save you from sending to these undeliverable contacts, and to help you maintain a clean list.
The next step would be to save a record of these contacts (if required) and delete them from your account.
Remove Deactivated, Bounced or Unsubscribed Contacts