Alternate approach, if you don't want to use a license:
Create an alias or distribution list pointing to your account. (Distro list would be to work around bug #40506 and possibly others.)
Then create a folder in your account to hold mail from customers.
Finally create a filter that files all mail To: or Cc: that address into the folder, and share the folder to your sales reps.
Note that there's currently no way to filter mail that arrives via Bcc:. But this "deficiency" is of minuscule importance to your needs, I'm sure.
See also
Bug 15395 – Optionally add X-Original-To header which discusses a possible solution to the Bcc: issue and also offers some other ideas.