When writing query letters, keep it short and sweet. If they have any interest in hearing more, they'll let you know.
But for the most part, these folks don't have time to read your long email. Don't give them a summary, particularly if this is an unsolicited query. Agents and managers don't want to be sued for allegedly stealing your material. Some companies will even have you sign an agreement before you send them any info on your script. Share with them anything that verifies you as a writer, like competitions you've won, representation you have, and your screenwriting accomplishments. Don't have any of those things? Consider first entering a competition and/or shooting the movie yourself! Be confident, but not braggadocious. Even if your script is going to blow their socks off, don't tell them it will.