If you get that Yahoo mail down on your iPhone device, then you need to change your settings. Actually, you are required here to remove and re-add the Yahoo mail to the iOS mail. Here, you are required to log in to your account again by entering the correct user credentials. For further issues, reach us....
If youre not able to compose the mails due to Yahoo mail downerror message, then you must check the internet connectivity or you can diagnose the problem using the techniques that are listed in the help center. In addition to this, you can call customer support for the necessary help.
To restore any emails, you can check the Trash folder of your email account. There are most chances that the missing or deleted emails move into the Trash folder, so you can prioritize it to restore for any emails. Form there you can press Move, Restore, or any available options, it is also the same, if...