How do I forward old root emails from the root mailbox to my address?

[Andreas Widerøe Andersen]

Hi,
On one of my FreeBSD servers all system emails to root is stored in the root
mailbox under /var/mail/root. I have updated my alias file so new mail is
forwarded to one of my email adresses, but is there a simple way for me to
send all these old mails in root's mailbox to my email address without
logging in through pop3/imap?

A command line trick would be perfect.

Thanks for your help!

Best regards,
Andreas