Set up many users on many computers with a single mail-in DB

What do you do when you need a few users on different computers to have access to one mail file (shared mail file) but don't need their own email address.

We just seem to have more and more storeman working on different shifts out in our warehouse who need access to an email inbox but don't actually need their own email accounts. These people move around the store and can work on any computer through the day.

I was thinking of registering each user but setting the mail type to *NONE and then in the mail field of their person doc pointing to the mail-in DB.

But is also seems a waste to register each user as the mail use is so limited. How does the licensing work for users? Is it each registered user? Could you have just one registered user and all these people use this one account on many different computers to access the mail-in DB? This would be heaps easier to manage now with the ID Vault and password syncing.

Hope this explanation is good enough.

Thanks

Nathan