Follow the steps below in order. After trying these steps below, you can solve the Yahoo Mail not working on iPhone issue: 1. First, need to check to see if your mail account works 2. Then, restart your iPhone 3. Update your iPhone device 4. Delete and re-add 5. After, change your email settings I hope, you may solve the Yahoo mail not working on iPhone easily after following these steps. If you want to know how to deactivate the Yahoo account issue then, you may contact Yahoo mail, perhaps there’s a service outage meaning Yahoo mail servers may be down. Read More: How to Solve Yahoo Mail Problems on iPhone and iPad?