Creating a suppression list or blocklist
We don't offer a global suppression or blocklist. Instead, we recommend importing your suppressed contacts into your list as unsubscribed:
When importing a contact list there is an option of whether the contacts should have a status of subscribed or unsubscribed. If you have unsubscribed emails to Import, separate the two list files then import them into the same Master list. Import your exclude list with the status unsubscribed. This will prevent those contacts from being re-subscribed if they are inadvertently imported into your list in the future.
All unsubscribed contacts are at a list level, as opposed to a global account level. As all lists are treated independently if you have multiple lists make sure you import your exclude list each time!
If you'd like it to affect currently subscribed contacts, make sure to choose the option to update existing contacts too.