Do you have to be subscribed to a topic to publish messages to it?

In my social network, I’m passing messages between users, by making their peerIDs into topics. Any message sent to another user is done so via their topic.

My question: Do I have to be subscribed to a topic for the recipient to get the message?

No you don’t have to, but I think you node will still join the other on the topic.

Your building social media, that’s cool me too!