I mailed back the Form 3531 and the printed Form 1040SR which the IRS had sent to me. They received the form on May 7th. I have yet to receive an answer as to where they got the Form 1040SR with just my signature and date, since I filed electronically.
I tried calling several times but never any answer by agent.
I don't think this was a phisihing scheme but I think it is a bit suspicious.
capnbobl1011
