New subscriber vs. Old subscriber?

New subscriber vs. Old subscriber?

I have different Sign up forms for different services on my website.  When someone uses a sign up form is there a way to automatically determine if this e-mail has registered before on any of my mailing lists?  

I want to be able to go...if they are new send them "X" e-mail which has an introduction to our company as well as sending them the information they asked for. 

If they are old send them "Y" e-mail which skips the introduction part and just sends the information they asked for.

Thanks for your help!