Where are email addresses coming from on my blackberry?

I have a new blackberry bold, and it appears to be cache'ing all email addresses from any opened email. It is not putting them in my address book but they are there cluttering up the to field when I type out a new email.. I have cleared all history and caches but they wont go away and i don't appear to be able to delete them individually. Why is this happening ? Where are they coming from and how can I get rid of the ones that are already there,,,and stop it from happening more.

thanks so much.

su.