A lot of mail servers are configured like that. Messages with very high SPAM rating are rejected, but still delivered into the SPAM folder. The server rejects

A lot of mail servers are configured like that. Messages with very high SPAM rating are rejected, but still delivered into the SPAM folder. The server rejects the message, to get rid of spammers. After a few rejected messages, they usually stop delivering SPAM for quite some time (it's unnecessary work to do, and a higher risk to land on blacklists).