Glass houses, you guys - it's not just the military
Shortly after I left Symbian in 99, to start up as in independent designer, I registered "symbain.com", after I mistyped an email and it bounced back.
I hasten to add this is all above board, as I use it to show people - the people who make this very typing mistake - that without user-centred design their security technology doesn't work: a little user-centred design and you just accept that on occasion we'll find ourselves unable or unwilling to encrypt everything, and on occasion we'll make addressing errors too. So email software ought to watch out for addressing errors - they're generally trivial to catch.
Anyway: emails still come in to "symbain.com" every day, and the commonest are from you techies, debating bugs and specs between Symbian and partner companies.
To me, though, it's just inevitable human nature, and it's the designers of the email programs who are at fault for such emails getting through.