You need to create new identities in Outlook Express.
If you look in Help in OE it will give info on adding/ managing these.
You will need to set up the individual mail accounts in each identity.
To add a new identity
On the File menu, point to Identities, and then click Add New Identity.
Type the name of the new user.
If you want to include a password for this identity, select the Require a password option, and then enter a password.
Outlook Express asks you if you want to log on as the new user. If you answer yes, you will be
prompted for information about your Internet connection. If you answer no, the current user remains logged on.