Some more advice on how to spice up the email: 1. Tell them they'll make lots of money from. Don't explicitly state this, but heavily imply it (despite the fact that they probably won't).
2. Insult their intelligence. This is especially effective with Math Rock bands, as they pride themselves on their intelligence.
3. Ignore step two completely.
4. Don't say ANYTHING about how much it might cost them in any way, shape, or form. This will be the biggest deterrent for any artist.
5. Don't point them in the direction of an authoring group with the group's prior consent.
6. Reference their lyrics in your email, but only deep cuts that you believe are personal favorites of the band, no big hits.
7. You're not a robot, and statistically people don't like talking to robots, even if they only vaguely feel like they're talking to a robot, so try to not sound like a robot.
8. Don't put too much in it or you will overwhelm them and they will not reply or even give it a second thought.
9. Don't attach a picture of the following: a. How big of a fan you are, b. A lolcat (only exception is Bicycle Cat, and even that is hit or miss depending on the bands nationality), or c. Elvis Presley album covers (unless you know they are Elvis fans).
10. Don't assume your email is being read by the band, as it most likely is being read by the manager or someone else loosely affiliated with the group.
That's as much as I can help on the subject.