Problem with "where's my refund"

[engrbobu]

My efiling was rejected by IRS even though AGI was correct (copied automatically from last year by TurboTax) and there were no problems with last year's return (also by TurboTax). After an unsuccessful attempt to repeat the efiling, I mailed in the signed return with more than enough postage. This was in mid February. Since then, I have used IRS "Where's my refund" almost everyday and response is "no record, check your entry". I called the local IRS office on April  4, and they could not locate my filing and suggested I "wait a bit longer". Filing deadline is approaching. What should I do to avoid penalty for non-filing if the post office or the IRS lost my paperwork?

[DoninGA]

The postmark on the envelope is your proof of timely filing of the tax return. 

If you are owed a tax refund the due date for the tax return is not applicable for tax refunds.  Tax returns with a tax refund can be filed at any time up to three years from the original due date of the tax return.

[engrbobu]

Thanks! Unfortunately I don't have the postmarked envelope - the IRS should have that, assuming the post office delivered it. Interesting to hear that the filing due date is different for refunds. Again, I greatly appreciate your response.