https://docs.customer.io/journeys/set-preferences-outside-center/
A subscription center helps you differentiate between the types of messages you send and lets your audience decide what kinds of campaigns and messages they...
subscription centersetpreferencesoutsidecustomer
https://docs.customer.io/journeys/migrate-subscription-prefs/
You may have managed your audience’s subscription preferences manually—with your own attributes in a system outside of Customer.io. Before you use our...
subscription preferencesmigratecustomerdocs