This is not true. They're not even making an effort and are quite probably actively malicious. There is nothing you can do to build up your reputation if you're

This is not true. They're not even making an effort and are quite probably actively malicious. There is nothing you can do to build up your reputation if you're a small email server. There are no introspection tools to give you a hint on what's wrong and no one to contact. Besides, what are those fancy ML antispam algorithms for if the only cure for spam is "reputation"? It's clearly an undefined term meant to be exclusionary. A person from Gmail even posted on HN a while ago, stating they'll look into this and do better. That was about a year ago and the situation is exactly the same or worse.