So, yes. Emails might work. You never know. Certainly people have tried before.
Llyn didn't say emails, though. She said 'snail mail'. Physical letters.
In order to increase your chances of a company at least giving you a quick listen, snail mail is the way to go. Anyone can write an email and send it out. Emails can be deleted, ignored. But with snail mail, there's effort. You have to buy the paper, the stamp, the envelope, write out your message, actually mail it. These are harder to ignore.
So if anyone is set on sending Universal letters regarding a next LBT movie, stick with the snail mail route. Never use email. Not if you really want them to take your message the slightest bit seriously.
Edit: And when you send your snail mail, please be formal and to the point. No need to say anything grandiose or over the top. Remember, this is a major company, not a high school club. Skip the lingo and write to them in a professional manner. You can still express your love for LBT while writing appropriately.