If you were able to get it before, and you were running Outlook Web Access, then you will can login to the BIS from the site or the device (email settings) and change the account settings, or delete and re-set it up.
For some reason, I cannot. I deleted the old one, but I now have to login as a different name than my actual email address. Say my email was my member name on this forum, rudy1082ATyyyycom, I now have a different login than my username., I cannot get it to login as one name, and have my email be a different name.