VPOP = VPOP3 Email Server
I think your boss may be referring to the VPOP3 mail server product.
Unfortunately (for some) that is a Windows product. I have used it for years on Windows 95b and it is a terrific piece of software. Well built and stable. Extremely easy to setup and maintain. Runs fine on a P2/350 that I've had sitting around forever.
As I said, the downside is that you have to allocate a Windows machine to run it.
Check out the feature list.
PS - If anyone knows of something with equivalent features AND similar ease of setup that runs on Linux, please let me know! Ideally one package that combines SMTP, POP3, gui setup, etc.