To stop (or at least decrease) the junk email, you can:
1. Create a separte email account for online purchases: Then keep that account’s inbox separate from your phone’s main inbox (and update selected vendors with the new email address). Check the special inbox occasionally, but otherwise let it collect all the noise.
2. Unsubscribe from vendors’ mailing lists: Do this ONLY if you know the vendor is reputable, e.g., a store where you’ve made purchases. Otherwise, you’ll get more junk because the spammer knows your email address works. The unsubscribe link is usually at the bottom of emails.