Depending on when you created your iCloud account, your iCloud email addresses and aliases may end with @icloud.com, @me.com, or @mac.com domains. Learn how these email addresses are granted.
If you created an iCloud account on or after September 19, 2012, your email address ends with @icloud.com. Learn more about @icloud.com mail addresses.
If you created an iCloud account before September 19, 2012, or moved to iCloud with an active MobileMe account before August 1, 2012, you have both @me.com and @icloud.com email addresses.
If you had a working @mac.com email address as of July 9, 2008, kept your MobileMe account active, and moved to iCloud before August 1, 2012, you can use @icloud.com, @me.com, and @mac.com email addresses with your iCloud account.
In each case, you can sign in to iCloud with either your @icloud.com email address or the Apple ID that you use with your iCloud account.
If you created one or more email aliases for your account, be aware of the following:
You can change or delete an email alias, but if you delete an @mac.com or @me.com email alias, you can’t add it back to your iCloud account.
You can’t sign in to iCloud.com with an email alias. Sign in with your @icloud.com email address or the Apple ID that you use with your iCloud account.