Comment by buzer

Assuming you are in EU you could report them to local DPA. Objection (i.e. unsubscribing. Original automatic subscription may or or may not have been legal) to direct marketing is pretty much absolute due to GDPR Article 21(2), I'm not aware of any "workaround" companies have successfully managed to argue.

In the US you can report it to FTC for CAN-SPAM violations, but don't hold your breath on any enforcement.