I manage my email address by not giving it out to random people/stores who have no need for it. Was at one of the big box home improvement stores last week buying some light bulbs. The cashier asked for my email address, told me it makes doing returns easier. Nope, I don't give it out.........they are light bulbs...... I have no intention of returning them..........problem solved. Most stores who randomly ask for my email, I just say "I don't give that out". Many of them turn around and sell it to some other company........if you limit who you give it out to, you can also minimize spam and junk emails.
Sometimes an online shopping site asks for my email just to browse their products............nope not falling for that. Plenty of other website to shop so they lost me as a potential customer...........LOL.