Late 8606

I am aware that you can file a delinquent Form 8606 on a standalone basis, without having to amend your tax return. Also, I'm aware that there is a $50 penalty unless you can show reasonable cause.

 

My question, is how can you verify that the IRS has accepted these forms? I mailed two delinquent forms years ago, and never heard anything. How can I check that they were accepted?