In principle I mean all internet mail, with only such exceptions that
have solid justification.
Even though mailing lists users are differerent in principle from the
general population, I've never found an exception I can formulate and
justify robustly. Fuzzy exceptions are easy to find. Exceptions based
on the population of unix types who were on the internet fifteen years
ago too.
One way to get a proxy for a general list would be to look at all
incoming mail at a couple of big ISPs in different countries. To the
extent the user-agent lists match, that should be a decent proxy.
If any big ISPs would play...
Arnt