Single domain licensing for Var's

Do you offer single domain licensing? We have many clients the we do web hosting for that have a local Lan Server that we manage for them including redirecting their e-mail to their in-house server and would like to standardize. we currently use webmin but would like to use VirtualminPro. No web content on these servers just the e-mail. It would be nice if you offered these in packages of 5 or 10 licenses for VAR’s to be able to use VM2 to handle administration.