Replying to the email can itself trigger further spam because it just proves there is someone home at your address. I know you don't want to change providers, but essentially you're asking for a feature (spam reporting, phishing reporting, hands-off unsubscribe) that your provider doesn't have. Moving from Gmail is awful but it can be worth it for features like that and others related to security (SPF, DMARC) and privacy (suppressing inline images, showing full link URls), etc.