In the email, there should be a link to review your return with a Rejection code that will provide more information. Please see the Help Article here to assist you with correcting and resubmitting your return.
I'm sorry it wasn't a email that I received. I was logged into my credit karma account and was trying to check the status of my return. That's when I was told i was still waiting on the approval. So I went to turbo tax and it was saying that state was denied. I've not received any email's from the IRS stating there were any errors.
Turbotax may show that your tax return has been accepted and that means it has passed the basic/initial filters like your name, SS#, birthdate, and that nobody else has claimed or file with your basic identity data. The IRS then may tell you that the return is not in the system. The reasons may be that the return was selected for review or audit. The IRS "where is my refund" page may say that there is no return in their system. You can call the IRS and they will notify you that your return is being reviewed and there are no dates in sight as to when it will be processed. What can you do? Nothing, other than wait patiently for the IRS to finish their review or audit and then they will issue a letter explaining what they reviewed/audited and the results thereof.
Hope this helps and best of luck with your return.