The domain is a major email provider, protonmail. They can read the contents and they already have the option to put it in a spam folder if it so heinous. They

The domain is a major email provider, protonmail. They can read the contents and they already have the option to put it in a spam folder if it so heinous. They could very easily elaborate whether it is the domain, my address or the content of a previous message that has resulted in the block, but no. They could simply do that instead of subtly encouraging me to use their email service, it is entirely their fault.