One time I worked with this girl at the library, back in college. She was beautiful without a doubt, and I was way too nervous to ask her for her phone number or anything, but I did make conversation with her. Anyways she left the job to work somewhere more related to her major.
The next summer, about 5 months later, I was still thinking about her (I guess thats what you guys call one-itis?) so I found her e-mail and sent an e-mail expressing how interesting I thought she was and how I wanted to meet her again.
I recieved an e-mail back and it took me about 3 hours until I gathered the courage to look at it, and when I did she said that she had a boyfriend. The letter was only like one sentence long, and was very curt. Anyways I felt devestated and I dwelled on that letter for the rest of the summer. And during that summer I can name you two other women who I had a chance with but didn't take it because I was dwelling on that letter.
The next semester I ran by her and her boyfriend at the supermarket. We made eye contact but I felt so awkward and like an idiot that I just walked past them.
Anyways sending an e-mail to express your interest in a girl is the wussiest and pathetic thing you can do. It signifies that you are going to take the initiative, but in the least resistant way possible, and that is probably going to be a turn off and make the situation really awkward every time you see each other in person.