Set Outlook/Exchange to display inbound to: addresses instead of mailbox name

I am afraid it is doing to be a client side rule..
For details :
http://office.microsoft.com/en-us/outlook/HP010524761033.aspx
http://www.slipstick.com/rules/serverbased.htm

If you want to be hassle free solution then split the mailbox it to two, Means create a new mailbox and remove any one SMTP address from resource mailbox and assign to new one (Change the display name of the mailboxes to classify the mailboxes). Assign full permission and send as permission for users on new mailbox and add this new mailbox to the common mailbox outlook profile. Please let me know if you need detailed steps.

Have a look at http://www.ivasoft.biz/whichaddress.shtml

Regards.
Victor

Well, that looks like it would work, but here's a way to do it without additional products, that I figured out myself.

Create a Universal Group, of type Distribution Group, for each inbound email address, named the user portion of the SMTP address (the part before the @).

In each distribution group:
>Assign the single SMTP address to the Distribution Group, format: <group name>@mycompany.com.
>Set the address list visibility off.
>Set it not to respond to return request.
>Make the departmental group mailbox the only member of each of those distribution groups.

Now, any mail sent to the smtp address assigned to the distribution group will land in the shared mailbox, and when you look at it, Outlook will display the distribution group name and not the mailbox name.  Since it's going to the shared mailbox, you have the single point of control for "generically addressed" emails you lose by giving each member of the department membership to those distribution groups, but you still give them an easy way to see which of those shared-mailbox messages applies to their job function.

Essentially, this works around the default (flawed, IMHO) behavior of Outlook/Exchange by using the default behavior of Outlook/Exchange of always displaying the "friendly name" (display name) of the recipient object.  Since the recipient object is actually a distribution group, it doesn't burn another mailbox seat but it still assigns the distribution group's "display name" to the message, which is what ends up displaying as the To: in Outlook.  Kinda kludgy, but what can you expect when you're working with Microsoft products ;)

Since the whichaddress product is something which also could be an answer to this issue (just not for me) I will do a split between the other useful comments and this one.