It possible to backdate emails?

A user's computer date was changed for whatever reason to a month ahead. It was like that for several hours before the user noticed it. She had sent and received several emails in that time and with the date being a month off, all emails were time stamped a month off. The date has since been corrected on the computer. The dates on the emails sent and received are still a month off. Is there a way to change all those emails to have the correct date?