Hi pad1999,
Welcome to the Apple Support Communities! You can think of the email addresses (and phone number, if you have an iPhone) in iMessage like the user or screen name in other messaging programs; nothing is actually sent to your email address, it's just a way to identify you so that other iMessage users can send you (and specifically you) messages. How it works is explained in a bit more detail in the following article:
Instead of using buddy names, you can send messages to people using their phone numbers or email addresses. If you entered their contact info in Contacts, you can enter their name and then select which phone number or email address you want to use to send a message.
When someone sends an iMessage to your email address, you receive it on all of your devices (Mac computers and iOS 5.0 or later devices) that are set up to receive messages sent to that email address. When someone sends an iMessage to your phone number, you receive it on all of your devices (Mac computers and iOS 6.0 or later devices) that are set up to receive messages sent to that phone number. When you view an iMessage conversation, you’ll see all messages including those sent from a Mac or from iOS devices, so you can talk to your friends wherever you are
Messages (Mavericks): What is iMessage?
Cheers