I manage a small department that uses a shared Outlook email inbox to communicate with our customers. Occasionally an employee will forget to add his/her signature to an email reply, thus making it harder for me to find out which employee sent the email.

Each employee has their own company issued PC with a unique login. I know that each email has a unique message ID (i.e. entry ID, etc). After an email is sent, forwarded, or replied to from our shared email box the the sent item is saved in the standard Sent Items folder in Outlook. Is there a unique identifier embedded in every sent email (perhaps the PC username, full computer name, etc) that I can lookup to identify who sent any email? Any ideas are appreciated, thanks!

Note: I'm unable to download any third party software so I'll have to build this from scratch. I'm vb savvy.