I have been getting a ton of junk mail in yahoo mail. I have been sending them to JUNK for a long time and they are still coming! How do I fix this?

Did a google search and one user suggested using the "block sender" feature in Yahoo Mail. Means logging directly into Yahoo Mail, but may be worth a try.

How to Block Spam in Yahoo!

1. Select the message or messages from a certain sender you want to block by clicking the check box to the left of the message.
2. In the toolbar at the top of your inbox, click the three horizontal dots next to the Spam button.
3. Select the Block senders option.

That is a Yahoo mail issue, and would have nothing to do with Apple. Check with Yahoo to see if they have additional options available that would help prevent so much junk.

Yahoo Plus Support - Customer Service You Need 24/7Ad·https://www.yahoo.com/

For what it's worth, I had over 150 junk mail messages arrive overnight. That's about normal for me.

Have you checked the settings in Yahoo Mail for a junk mail filter? You might also check Settings > Mail on your phone for such settings.