Will Lemmy spam become like email spam?

My understanding of federation is that it's like email. If one server is misbehaving, then they get defederated.

So how come email spam still exists - why don't spammer domains get defederated? It seems like we've got the worst of both worlds, where it's hard to get your emails relayed when you run a small email server, and easy to get them relayed if you're a spammer.

Is there anything about Lemmy's architecture that will prevent this problem?