How do I associate an existing gamer tag with a different email address?

I'm having a different type of issue. The gamer tag that is associated with my email is wrong and I've never used it before. However,on my xbox, the correct gamer tag is there as well as the correct email address. How do I fix this?

Thanks Clint

first of all you can not have 2 different gamer tags on one email address so there must be a different email address associated with the original gamer tag your best bet would be to contact xbox support at support.xbox.com/contact-us and give them your gamer
tag and if they can verify your account they can give you the email address associated with your original gamer tag

The only reason it would have brought up a different gamer tag is if you signed into a different email address.

At this point if you do not remember the email address associated with your original gamertag you can contact xbox support by going to support.xbox.com/contact-us and requesting a call back or talking to a chat person give them your gamertag and if they
can verify ownership of the account they can give you the email address that is associated with that gamer tag

If you are seeing a different gamer tag that you normally use, first indication is that you are using the wrong email address that is associated with your gamer tag.

You signed in with a different email than what is with the account that is associated with your xbox 360 profile you can find the email associated with that profile by signing in on the account on the 360 going to settings and account and then billing info
and it will show you the email address that is associated with that gamer tag