My name is***** am sorry to hear that you are having this issue.
I will be glad to assist you with this.
Try these steps please.
If your Yahoo Mail settings are corrupt in iOS Mail (the "Server Unavailable" error), the only way to fix it is to remove and re-add Yahoo Mail.
Remove Yahoo Mail from your iOS device's native email app. Here's how.
Then readd and Make sure your settings are correctly configured.
If your info matches, checks will appear and you'll return to the previous screen. If not, you'll need to use a computer to verify your login details.
Let me know if this does not work and we can try another solution.
Please reply and let me know if you need any other assistance,
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