The question has been asked many times how can I validate a email address? As you would expect the answer is deeper than just do a line of java script. Which one could use a java script to assure that at least the formatting is correct. A good simple sample code can be found here. "Click Here" 

If you want something that can actually Helo a email address to really know whether or not the address is bogus or not this will require a component. My personal favorite can be found here "Click Here".