Apple is a company which ensures the most reliable and secured devices and services. And its iCloud mail also does not arise issues commonly but a few times it creates issues such as not receiving mail on any device. There are some reasons behind this issue:
- Unstable or Poor Internet Connection
- During the backup process of iOS or iPadOS, all the emails have been deleted but only the email settings stay the same, So be careful while you create a backup
- Service Outages can be a Reason Sometimes
- Using an Older Version Also can Let You Raise this Issue.
Resource URL: https://emailspedia.com/icloud-is-not-receiving-emails-on-iphone/