Thanks for getting in touch, kaci226.
It looks like you're having trouble with your iCloud Mail. We can help.
When you have a chance, check out this article: If iCloud Mail isn't working
"Things to check first
- Check the system status of iCloud Mail.
- Check that you turned on iCloud Mail:
- On your Mac, open the Mail app then choose Mail >Preferences. Click Accounts, then select your iCloud account in the sidebar. Under Account Information, make sure that the account is turned on and the status is online.
- On your iPhone, iPad, or iPod touch, go to Settings > [your name] > iCloud and check that Mail is turned on.
- Make sure you that haven't exceeded your iCloud storage limit. If you exceed your iCloud storage limit, learn how to make more space available in iCloud.
- Make sure that you're using the latest version of software on your device."
There are additional steps from this article that may help. This is another great resource to review: Mailbox size and message sending limits in iCloud
If this article doesn't help and you're still getting the error of full storage, contact Apple Support.
Take care!