What exactly does the reject email say? And who is it from? Maybe its a fake. Or an old email for a prior year?
If you efiled, In the PDF of your TurboTax return, the last page of the federal return should be an "electronic postmark" that shows your name, Social Security number, the date and time that you e-filed the return, and the date that the IRS accepted it. For Desktop You can probably switch to Forms mode and get it.
If your return shows Accepted then I wouldn’t worry about the email. You can also order a Transcript from the IRS to see if they got it.
https://www.irs.gov/Individuals/Get-Transcript
