" I want to file by mail."
I understand that. However, if you clicked that big orange "TRANSMIT RETURNS NOW" button, then you e-filed. If you got a "successfully sent" message, then you have e-filed your return. So you need to confirm BEYOND ANY DOUBT WHAT_SO_EVER that you did not e-file your return. Don't change anything on your return yet. Just confirm that you know for an absolute positive fact, that you did not e-file.
If you e-filed the return, then you mail it to the IRS, that's an automatic flag for potential fraud. So that's why this is important.
