Hi vendimb15716755 ,
I'm not sure what your preference center is designed to do but I suspect, it is there to
1. Unsubscribe the recipient from a specific service like newsletter.
2. Blacklist them from Emails.
If option2 is correct, your PC should be marking the field @blacklist in Recipient schema to 1. If it is happening, all deliveries by default are designed to exclude such people. If the value is not getting set to 1, please check the PC logic to see if it is updating a different column or updating nothing. You might have to fix the target mapping blacklist logic to suit your needs.
If PC is designed for option 1, it will not mark a recipient as blacklist. they are not supposed to just receive a particular newsletter thats it. They should receive other emails.
At the time of targeting you should be adding a filtering condition that people who are subscribers of a service should only receive your email
Regards,
Vipul