if what you are talking is recalling a message you sent. thats impossible . that only work on a MS exchange server. but if it's a message you delete and want to get it back. the easiest way would be to get it from your sent items. if not call the comapny and hope u get a excellent tech that would be willing to help you. the next step is if you are geting your road runner mail throught a 3rd party mail program, say outlook express or microsoft outlook. all you have to do is delete the email account. and all offline/backup file associated with the account. then recreate the account, it will re download all your message sent, received, draft, deleted since you last did a send and receive.
I think he had mentioned already that he knows he can retrieve it from outlook. Still, lets make this sure that, Did he configured the roadrunner account on outlook? or is he saying about retrieving the messages from road runner web mail account?