I don't have an overloaded inbox, but for those who do, it seems to me that they're mostly overloaded with stuff that was sent to a group rather than to them as

I don't have an overloaded inbox, but for those who do, it seems to me that they're mostly overloaded with stuff that was sent to a group rather than to them as an individual. If the sender is even thinking about the question "Does this particular individual have time to read this email?" then the chances are that this email is already far more important than average.