Make it interesting and share your story.
In an age where things are almost always impersonal, sharing the story behind your song helps writers better understand why this song—your song—is so important. While being to the point is always appreciated, generic emails that contain no thought are easy to pass. We read hundreds of similar emails every day, so think about what you can do to stand out, whether that's by making us laugh, getting us invested in you as a person, or carefully using an element of mystery.
Make it interesting for us, give us something we want to share with the world. When you're passionate about your work, it'll show, even in an email.