Google does this as well - neither a history of emailing back and forth nor a same-day reply will keep incoming email safe from being classified as spam if it's being sent by an ordinary mail server.
Hell, Google even manages to classify emails as spam that are sent from one address on a GSuite account to another address on the same account.
Hell, Google even manages to classify emails as spam that are sent from one address on a GSuite account to another address on the same account.