I used a one-off email address to register for SGT, so anything sent to that email address will "bounce" as it is inactivated. I assumed everyone does the same, but apparently not. The alternative is to use a service like MaskMe. The one rule everyone should follow, especially on the Internet, is never, never, never give out your real email address. My invariable habit when some impertinent person asks me for my mobile phone number is to give them one - just not mine.