The Intuit Postmark reports that the return has been accepted immediately after you send it but it does not report the submitted date and time.

We normally print these reports and attach them to our PDF copy of the return to as proof of filing.  After the return is accepted, the submission date and time fields of the report populate, but if there is a problem and the return is not accepted you have no proof the return was submitted timely.

It didn't work like this last year.