Where does the NDR come from?

[Doreen]

Someone just sent out a meeting invitation to all the attorneys in my firm.
She got two NDR's from secretaries that no longer work here, obviously b/c
they are still delegates on someone's calendar. Without going to every
possible attorney that these two people worked for, is there any way of
knowing which accounts triggered the NDR?

I tried tracking the NDR message in Exchange, and I can find it, but it only
tells me who its going to, not who it came from.

Any ideas?

Doreen