You've Got Mail as an YA urban fantasy

When I first started reading this it seemed very much like the movie "You've Got Mail" where rivals end up emailing each other and falling in love. Where he knows it's her before she knows it's him. I enjoyed the urban fantasy element of this premise with an enchanted typewriter being the "email" conduit of sorts. What made this stand out was the high stakes of a war between gods in which mortals were called to fight. By the time I was toward the end I wanted to cry and scream.