"Creepy" app helps you write perfect emails to anyone

A new app that pulls information off the Internet to improve the average email has even the creator calling the new technology "creepy."

Drew D'Agostino is the man behind Crystal, something he calls the biggest thing to hit email since spellcheck.

"Crystal tells you how to communicate with anybody. And, to get that information, it detects information written by you, or about you online," D'Agostino told CBS News San Francisco's Betty Yu.

So, if you want to write an email to someone, Crystal will scour the Internet to find whatever public information is out there about that person and develop a character profile.

"That's where you get these insights that say, 'this person really likes short emails, and they get right to the point,' or, 'this person needs a lot of detail; this person likes structures and rules; that kind of stuff.'" D'Agostino said.

The app will then tell you how and what to write -- or not write -- coaching you toward an email worded specifically for someone else's communication style, something D'Agostino says "is an example of how technology can bring the personal even more into the focus."

On the website it explains, "When you write an email, Crystal tells you the words, phrases, style, and tone you should use to reach the recipient in the way that they like to communicate, rather than your own."

Even D'Agostino admits the app may seem like a violation of privacy to some.

"When you first see it, everybody has this weird reaction of, 'this is kind of creepy, but this is also really powerful.'"

Crystal doesn't perform any special kind of background check, only using information that is publicly available. The founder says the accuracy rate is about 80 percent.