After you file

I simply want to know if the IRS received my tax return. It was e-filed on Feb 21st and I received an email from TurboTax  a day later stating that  they did.

However,  after 18 days, I'm still getting the same 'You need to wait 24-48 hours'  message. Since the IRS site will not give me my status,  I'm wondering if  they actually  received my tax return.  How can I be assured that they did.