Hi jambon212,
We take your privacy very seriously, and understand that you've blocked a phone number on your iPhone, but are still receiving iMessages from someone through the Messages app on your MacBook Pro. To clarify, did you block all of the contact details and email address on your iPhone as well, or just the phone number? From what you're describing, it sounds like maybe only the phone number was blocked, and the contact is still able to reach you using your Apple ID email address associated with iMessage. Here's how to make sure all of your contacts are configured the way you'd like on your iPhone and MacBook Pro:
Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch
Block texts in Messages on Mac
Please let us know if you have any other questions or concerns, and we'll be happy to assist.
Take care.