iCloud Mail seems inactive

Do you actually see any error messages, and if you do, what do they say exactly?

Have you tried sending an email to yourself? If nothing is happening then it may be a connectivity issue. Restart your equipment and/or sign in out and back in again, and try again. On a computer you can also try Safe Mode https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/12.0/mac/12.0

Choose your macOS version at the top.

If you can't connect or sign in to iCloud or your account, Apple has a list of things you can try in the support article: https://support.apple.com/HT203512

Is the appropriate Apple server working? --> https://www.apple.com/support/systemstatus

If your device is managed by a school or organization you may need to sign in to the device with a school or work Apple Account. More in this article —> https://support.apple.com/122725

If you are using a VPN try removing it completely (don't just turn it off) and see if you can then use the service. E.g., https://discussions.apple.com/thread/254836813?answerId=259008052022#259008052022

If using cellular data (even if it is seemingly good), try using WiFi instead. —> https://support.apple.com/HT202639

For more assistance try the iCloud Support web site --> https://support.apple.com/icloud

If you still have problems try official Apple Support. Click here --> https://support.apple.com/choose-country-region Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.