automatically noting who replied to email from group mailbox?

Hello Experts,

I am trying to overhaul a couple of internal processes and hopefully you can help me.

Here is my currrent setup:
Exchange Server 2003 SP1
Outlook 2k3 clients
20 customer service reps

For each new customer we create a mailbox for that account and a corresponding profile on each CSR's Outlook. When the reps need to access an customer mailbox, they log off of their account, scroll through the profies until they find the one they need, then open that mailbox and respond to the email. The logic here is they want the reply to look like it came from the mailbox and not an specific individual and a copy of the sent item to be stored in the account sent items not the CSR's. To help track who sent the reply to the customer, the CSR should type their initials into the bottom of the reply.

Here is what I would like to do:

   1. Create either a group mailbox or mail enabled public folder and grant the CSR's full access to it.
   2. Set it up so all of the mailboxes or folders are visible in the navigation pane of their own Outlook profile.
   3. When replying to an email message, the reply needs to look like it came from the account mailbox not the individual CSR
   4. All Sent Items and Deleted Items need to be in the account mailbox folders not the individual CSR's.
   5. Automatically inital or tag the responses with a unique ID that corresponds to the individual CSR.

I know that the first three items are easy; #4 and especially #5 are where my difficulties reside. I need to meet all 5 conditions or else I have to keep the old clunky manaul process in place.

Mikel948