Hi there, it has been a year now and I can't remember exactly what happened. But I remember I looked up the USPS website, filled a complaint, they got back to me saying it's still under processing. However, while waiting for a USPS reply, I mailed my return with a cover letter explaining the situation. A few weeks later, I got my tax return. But still not sure whether it was the first or the second mail that worked.
Hope it helps.
