I have 2 T of iCloud storage.
Why won’t my yahoo email download?
iPhone 14 Pro, iOS 16
Question marked as
Mail gets downloaded to the device locally, and not to iCloud.
You’d need to transfer the mail from Yahoo mail to iCloud mail to get that storage used.
Not to device-local storage.
Here is an intro: What's the difference between device storage and iCloud storage? - Apple Support