I have wiped all data from my phone, though after the factory defaults are set, my new e-mails from my work address start appearing in my phone, even though I didn't set up my e-mail yet?!
You have to shut off you BIS settings from your carriers BIS site. If you are on BES then you have to contact IT and tell them to remove you from the server. Just Wiping the handheld will erase all nonfactory items from your BB but email will still come if you dont take the steps above. Hope this helps.
I am an admin on the BES, I deleted my account on the BES, then wiped the handheld, which appeared to work, but then when I recreate the account on the BES, before activating it on the phone, the new e-mails appear again. Is there something else on the BES I need to do?