Dear Tuxedo 4910,

are you using Exchange Server or single Outlook installations on the
clients?

Without Exchange you could try an IMAP account as a "shared inbox":
http://www.slipstick.com/addins/services/online.asp

Another idea could be a 3rd party tool which can share PST files /shared
inbox. The clients can share all the central incomming emails and they can
answer this emails.

The product: http://www.publicshareware.com/

An FAQ:
"How to send and recieve emails in a Public Folder? (How to share the same
email account in a central public inbox?)"
http://www.publicshareware.com/tbl_select_antworten.php?id=68

Other Outlook sharing solutions:
http://www.slipstick.com/outlook/share.htm

Article about "sharing your Outlook information (by Eric Legault)"
http://office.microsoft.com/en-us/outlook/HA011477571033.aspx

Office Marketplace Outlook messaging tools:
http://office.microsoft.com/en-us/marketplace/CE010719621033.aspx

Maybe it helps.

--
Oliver Vukovics
Share Outlook without Exchange (Vista Ready): Public ShareFolder
Synchronize Outlook between PC and Notebook: Public SyncTool
http://www.publicshareware.com