Comment by placatedmayhem

Or, use a service that lets you generate an address for each business you deal with or use case you have so you can treat them as disposable. After chasing down spammers and companies selling my info, including my email, I found this was easier to keep up with and is more effective. Spam me once or sell it to another company, and I burn that address, replacing it with the original company if I really need them to keep in contact.