if it "exists"? i don't think so. the only way to accomplish that is to actually send an email to the address, and see if you receive a reply from the admin(system) saying it's invalid.
the only way to validate that the information itself is valid is to do some string comparisons, finding the original (address) portion up to the @ symbol, then finding the remaining host information (i.e. hotmail) and then the affiliation (i.e. .com or .edu).
that will let you know whether it's a "valid" address...but not that it exists.
Lian Li Lancool First Knight Series PC-K59W
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EVGA X58 FTW3 132-GT-E768-TR
EVGA GTX 660ti
G.SKILL Ripjaws Series 12GB (3 x 4GB)
Crucial M4 128gb SATAIII SSD x2
Crucial M4 256gb SATAIII SSD
Corsair Professional Series HX850 PSU
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Sennheiser PC 350 Headset
Saitek Eclipse II