How Do I Stop Giveaway Emails?
Entering giveaways puts you on marketing lists, which is the arrangement. Getting out of it is straightforward for legitimate senders and a matter of filtering for the rest.
Unsubscribe works on real senders
US law requires commercial email to carry a working unsubscribe mechanism and to honour it within ten business days. For a real company, clicking it is the fastest fix and it does not confirm anything harmful.
Do not reply to the obvious junk
For mail that is clearly fraudulent rather than merely unwanted, any response including an unsubscribe click confirms the address is live. Mark it as spam and move on. The two categories need opposite treatment.
The setup that prevents this
Use one email address only for entries, filter it into its own folder, and never point entries at a work address. Do not abandon the account entirely, because prize notifications arrive down the same channel and often land in spam.