I posted that response :) The members of MAAWG often keep and talk about these sorts of statistics too, although I wasn't able to find anything public (and I'm

I posted that response :) The members of MAAWG often keep and talk about these sorts of statistics too, although I wasn't able to find anything public (and I'm no longer a member so can't search the private archives any more). One thing worth bearing in mind is that Google's traffic is probably heavily biased towards consumer email. Business traffic may have a different profile.