iCloud: Set up an @icloud.com email address
If you set up iCloud using an email address that doesn’t end with @icloud.com, @me.com, or @mac.com, you must set up an @icloud.com email address before you can use iCloud Mail.
On a an iOS device:
Go to Settings > iCloud, turn Mail on, then follow the onscreen instructions.
On a Mac:
Open iCloud preferences, select Mail, then follow the onscreen instructions.
After you set up your @icloud.com email address, you can use it to sign in to iCloud. You can also sign in using the Apple ID you used to create your iCloud account.
You can send iCloud email from any of the following addresses:
Your iCloud email address (firstname.lastname@example.org)