Apologies in advance if you know this already but for those not in the know ...
This is prolly old news too but I only came across it a few weeks back !
This is because I had been creating virtual email addresses from my domains when registering with sites been doing that for years but this way is much neater
We all know that when registering with a site our email addresses somehow despite assurances still gets onto a spammers list.
A few weeks back I came across several plugins for firefox that allow you to create a temporary inbox where the registration site mails your activation code... Once activated you can discard the temporary email or even forward it to your real email address.
Here are some plugins : I personally cant remember the one I used but it was downloaded from mozilla extensions.
https://addons.mozilla.org/firefox/2650/
https://addons.mozilla.org/firefox/1813/