[exim] Reinject Email

I need to be able to reinject email from the /var/spool/mail/{user} file
back into exim for delivery to the original recipient. Last week I had to
put my server in place as a backup for another client while their hardware
was repaired. Now that their email server is running again, they want me to
take the contents of their mail file on my server, and send it to their
server.



I know I could forward the messages, but then the "FROM" and original date
and time will be lost.



I do not have the option of moving the email file to the new server, as the
formats are different.



Does anyone have a suggestion how I can accomplish this?



Thanks in advance

Terry