(Ted Schadler, ZDNet) After a survey of 53 information & knowledge management professionals to ask about the cost of email, it is abundantly clear that few firms know their true cost of running email on-premises. And this matters if you’re considering a move to cloud-based email.

While the cloud-based cost of email is pretty transparent (many providers, including Microsoft and Google, publish their per-user per-month costs), the cost of running email on-premises is often a big mystery to everyone, including most CIOs. The big challenge is that the costs are spread throughout the budget: some in the hardware budget, some in the software budget, some in the storage budget, some in the cost of capital budget, some in the staffing budgets, and so on.

But it an accurate calculation of on-premises email also matters if you are contemplating upgrading your email to a more current version that might support cheaper storage, higher automation, or reduced email database size due to eliminating redundant copies of attachments. You can compare your current costs against the fully loaded costs of the new system with its higher efficiencies.

When you factor in servers, storage, server software, software maintenance, hardware and software administration, power, archiving, message filtering, mobile costs, even financing, you find out that the cost of email for 15,000-person organizations can be as high as $40 per user per month, and even for a normal information worker without mobile email, it can cost more than $27 per user per month. Of course, you can and should segment your workforce into different tiers — for example, mobile executives, information workers, and occasional users — and provision them with different size mailboxes, email clients, and mobile email.