Apple ID

Make sure that the email you have typed in is spelt correctly. You may have also added the email you were trying to add before.

For more tips:

About your Apple ID email addresses - Official Apple Support

You can't add an email address to your Apple ID. Your Apple ID is an email address.

It sounds like you are trying to change your Apple ID to one that cannot be used. This situation often develops because the Apple ID is being used by someone else or you are trying to use an Apple ID that is, or was, in some way, associated with another Apple ID of yours (e.g., as a reachable at email address or a notifications email address) in recent history.

Note that you can't reuse an email address as described in the second case until an uncertain period has passed--sometimes reputed to 30 day and sometimes 1 year. Also, I have seen that you never can use such an email address again. The last two times I saw someone claim a time period it was “up to 30 days.” I believe that up to 30 days is the current answer. But, you can contact Apple support to check out the currently quoted wait period.

 Get Apple telephone support for help using this link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362 Be patient sometimes Apple support is closed to immediate phone support.