If 20% of people who seek you out actually volunteer, what's the fraction like for those that don't seek you out? 1e-8? So that email is worth over 20 bits of information? Maybe we have very different definitions of "almost no information", but it seems to me that email is quite valuable even if only 20% do a single assignment, and still quite valuable information even if only 20% of those do anything beyond that one assignment.