Nana24Diane Said:
"Yahoo Email on iPhone and iPads: An email from yahoo mail is received with an error message 'This message has not been downloaded from the server.'' I fixed the Fetch settings. The email will download on my Mac but not on my iPhone and iPad"
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Troubleshooting iPhone and iPad Mail:
A. New App Password:
Note that you would need a new App Password, being that Mail is a third party app. You cannot log in using your eMail address password.
The Yahoo! App Password Link: Generate and manage third-party app passwords | Account Help | Yahoo
B. Use WiFi:
I see you are using cellular. What happens when you use WiFi? Any difference?