Recruiter-Rater

I receive emails from this recruiter several times a month, actually received one today. The job of course sounds to good to be true. As the saying goes if it does then it usually is.
On one ocassion I replied to one which was a contracting position with AT&T. The recruiter replied asking me for my SS#. In turn I asked her why she needed it, and needless to say I never heard another word from her.