Using Outlook, each user must have an email profile created within the user profile on each computer used.
One way around creating profiles on each computer for every user would be enable roaming profiles (Profiles are stored on the server and downloaded wherever a user logs on. Be aware that the entire profile is downloaded when a user logs on a computer, and is resaved to the server when a user shuts down/logs off a computer. Depending on where users save work files (My Documents on local computer (which is part of a user's profile), or to a network share), and where email is saved (to individual .pst files (which are part of a user's profile) or user's Exchange mailboxes), users could experience extremely long log-on and log-off processes when using roaming profiles.
You might consider using Outlook Web Access (OWA). Using OWA, users are essentially accessing a webpage that contains the email in the user's Exchange mailbox. Since the mailbox accessed is dependent on a supplied userID and password, nothing is saved to a user's profile. This alleviates the need to create an email profile for each user on eahc computer.