If your form 8949 shows "M" in the code column, that is a summarized 8949.
The summarized form 8949 goes with your e-File (don't mail it again) ,the details are supplied by you separately.
If you have code M, you elected the mail in option, knowingly or unknowingly.
If there is no code M, then all the required details are already in your e-filed tax return.
