I haven't received any such mail this go-around, but I did with the worm that did similarly nasty things a year or so ago.
I simply wrote a note to the unknowing "offender"- - CEO of a consulting firm - - describing my receipt of a "fake message" from his computer, enclosing an account of the worm, then extant.
He then, and quickly:
1) cleaned his own address book - who else could have?
2) sent a note everyone in that address book describing the problem, apologizing, and urging WIN operators to chek their own ADs to slow down its spread.
Don't know what else could have been done.
ilw-00
Some time ago, a major Mac guru wrote that, roughly speaking, the recorded history of WIN vs. Mac viri approximates the following: WIN N= 38-39,000; Mac N = 8
That, perhaps, is reassuring.