Suppressed contacts fall into two groups. There are those contacts who have made a request to be unsubscribed from your emails. Additionally, you might have uploaded a specific list of email addresses that must never to used - this is a suppression list.
You must always give your contacts the opportunity to say that they don't want to receive any more of your emails. This means including an unsubscribe link in your email.
If you are moving to Sentori from another email service provider it is a requirement that you load a list of those contacts who have historically asked to be removed. This will prevent them accidentally being loaded as a contact, and their unsubscription request being dishonoured.
You might also want to load a 'hands off' list of contacts who you simply never want to get emails from you. These might be competitors for example.
Whatever the reason Sentori provides a mechanism for loading a suppression list.