G'day Pete,
There are many many admins who never do something sufficiently contentious to warrant the use of email. I personally have made admin actions numbering in the hundreds and have _never_ been emailled about them.
Only if you are going to go round contentiously banning people do you need your email available....
I (like to think I) have never gone around "contentiously banning people", but I receive emails about Wikipedia all the time ... sometimes even when I'm on wikibreak.
Perhaps I just have an open, inviting face?