Before changing deep settings, rule out simple connectivity or app glitches: How To Fix Email Not Working On iPhone?
If your iPhone stops downloading mail, it typically points to a sync error, a network glitch, or outdated settings in the Mail app. Whether you’re seeing a "This message has not been downloaded from the server" error or your inbox just won't refresh, you can usually fix it with a few targeted adjustments. 1. Initial Troubleshooting Steps iphone won't download mail