Shared email

I have just upgraded a PC to W2000 professional. There were two users at two PCs that use the same email address. Since upgrading to W2000, the user at the other PC now does not get to see the shared mail – it all goes to the W2000 PC running Outlook 2000. They connect to an exchange 5.5 server. The other user has W98 and Outlook 97. I can not delegate because they are the same email address (They have seperate NT logins). Can someone please explain why they are no longer able to share theirmessages

Thanks in advance