'This Apple ID is valid but is not an iCloud account.'

This message usually turns up for Windows users who are trying to create an iCloud account (they can't). On a Mac it's more difficult to explain. If you are one of those long-term users whose Apple ID is just a name and not an email address, you won't be able to create an iCloud account: the ID must take the form of an email address. You would need to go to http://appleid.apple.com and change the ID to a non-Apple email address which isn't associated with another Apple ID.

Well I am having the same issue. Ever since Apple demanded that i change my Apple ID password to make it more secure, I can no longer use iCloud email in Mail.app on Mavericks on my MacBookPro. When i tell Mail's accounts pane to make an iCloud account, i use my xxxxxx@icloud.com account and get the "This Apple ID is valid bit is not an iCloud account" error. I can still get my iCloud email on my iPhone. I have tried many restarts as suggested in other forums, to no avail. I have had my Apple ID since the day iTools was released in 1999, so yes I am a long-term user but my account has always been either a .mac or .me (and now .icloud) email address. I have tried using my .mac and .me addresses also for mail.app and it gives me the same error.

Forwarding my important mail from my phone to a dummy gmail account is getting old. How can an @icloud.com account not be a valid iCloud account on my computer but it is valid on my phone? I feel forsaken by Apple, but i suppose I shouldn't take it personally. This should not be happening.

You're right, it shouldn't. However you shouldn't need to make any changes in the Mail application. Try signing out in System Preferences>iCloud and then signing back it (perhaps after a reboot, though that probably isn't necessary). Obviously all your synced data will disappear from your Mac when you sign out, but will reappear when you sign back in (give it time).

Thanks Roger for your comment. Two weeks ago I did sign out in the iCloud System pref pane, that was probably the wrong thing to do since I lost all of my calendar information, all my iCloud mail and all my IMAP folders are gone. I followed the information in other support posts that said to sign out and sign back in and don't worry about telling your machine to remove everything from all those apps, it will come back. Maybe a restart or 3 would be required. I have restarted every day over the last two weeks - no luck.

What is odd is that my AOL iChat login *does* work with my new password. I had to change it in the iChat application - couldn't believe that worked sincet AOL has been sending nastygrams about having to dump my @mac.com login because they won't accept them anymore. But the text message link to my iMessage account does not work.

Is a clean install of Mavericks the only option? Thanks for any help you can provide.

same problem. i upgraded my iphone and ipad to ios 9. apple demanded i change my password. and a few hours after i did i couldn't login to my mac's mail, contacts, calendar and god knows what else. really frustrating.

I hope you can help me too. My problem is that I'm trying to create a (new) icloud account because they don't recognize my password in the old one; when I tried to reset it, they answered that they don't find an account for that email address. A vicious circle that I thought I could break by creating a new account, but the verification mail has not arrived to my primary address (more than 6 hours have elapsed). And I cannot proceede without confirming that address. Curiously, they did asked to confirm rescue e-mail address, which I dis, and they accepted. Any suggestion will be appreciated.

Go to https://getsupport.apple.com . Click 'See all products and services', then 'More', then 'Apple ID', then 'Other Apple ID Topics' then 'This topic is not listed'. If you have any problems with that try this form: https://www.apple.com/emea/support/itunes/contact.html