by Steve Ambro v2.7+.
Although I had already hidden the e-mail header using the line of code I had shown, plus one for the column, when I hid that option as you indicated, the e-mail column was no longer available in the grade sheet but then all columns from c3 and up shifted down by one. Columns/headers I had previously hidden above C3 shifted their hiddenness / visibleness to other columns. Hmmm Dilemma!
What other locations does your suggestion have effect?
I am not sure which method I should use.