If you can't unsubscribe and they're marketing emails take them to small claims in violation of the CAN-SPAM Act [0] if you're in the US. Liabilities are over $50k so you can easily max out the $10k limit in court with no representation. In this way it forces them to come to you and they will almost surely lose or settle before the court date.
[0] https://www.ftc.gov/business-guidance/resources/can-spam-act...