I have a personal domain on google apps. The login ID is different than the email address I use/advertise.
e.g. my username for login is first-initial+last-name@[domain].com
But the email address I use for everything on that account is first-name@[domain].com
This service states that my account was compromised on 12/12/2010 most recently at the first-name@[domain].com though you could not login to my account with that email address...
So - how valid is such a check. Also - without it showing what information it is checking against, it feels really spammy. as if they are asking you to enter your email for a "check" knowing that you will enter a valid email - then they harvest the email as valid for spam.