Each e-mail address has its own icon that the emails for that specific account go into. The "Messages" folder is for all of your e-mail accounts, if you had more than one. In your case, you can just hide the icon that has your e-mail address.
The Message folder on a BlackBerry is always present and cannot be deleted. By default it contains all your messages: incoming and outgoiing, texts and phone logs. It can be highly configured to chsnge those defaults.
But it will always get all your email messages from all your accounts. And every email account has its own icon as well, so messages appear in both folders. Best thing to do if you find it annoying is to hide it. Highlight icon > MenuKey > Hide
Edit: Wow, several people slid in ahead of me while I was typing, or maybe I didn't refresh the wap scren. Fortunately we kinda have the same thing to say :-)
Posted from my CrackBerry at wapforums.crackberry.com
Think of them as "links". There is only one message on your device, but two ways to get to it.
This makes a lot of sense... i was wondering about how much space all those messages were taking up too!
I've got three e-mail addresses set up on my curve right now... plus Gtalk and BBM, and twitter.... which i use WAAAAY too much!
I have this *hobby* of finding as many ways as possible to send a message!