You're correct that a lot of senders have no idea when they're sending unwanted email, and that unwanted email is well within the realm of possibility here. But don't assume DOI is a panacea; you can use DOI and still send unwanted email. It can improve quality metrics (fewer bounces), but engagement metrics are a much stronger signal, especially for gmail.
Can you think of a scenario where a well-intentioned organization doesn't realize they're sending some unwanted mail, and by looking at the right metrics they realize they have a problem and take steps to fix it?
