How does email opt out work

In terms of opting out of emails, there are two options;

Set a record to deleted - This makes it easier to make it active again.  

Unsubscribing a record - When you unsubscribe a record, remember that it might be added to the Campaign Monitor suppression list or will set other membership records to unsubscribed depending on your settings.

Opting out of emails is a complicated flow, so we have put together a comprehensive guide please see - 

https://www.beaufort12.com/campaignmonitor/support/email-opt-out