Do you use Gmail?
If you do, you will have noticed that Gmail changed it’s interface. Instead of having one inbox screen, you now have three inboxes separated into tabs. You have one tab called Primary, one called Social and one called Promotions. Email from email@example.com is likely landing in your Promotions tab. All you have to do to get these emails to show up in your Primary tab is just to drag and drop it from one tab to the other.