How do you compare Gmail and Outlook? In some surveys, Gmail trounced Outlook with a whopping 70% of the vote. Outlook had 19% while 11% of voters declared the two email solutions equal. Whatever your preference, let’s compare the two in terms of cost.

Email isn’t just about the client software—it’s not just Gmail’s web interface vs. Outlook’s desktop software—it’s also about the servers supporting that client software, and that’s where Gmail truly shines.

CIO Magazine reported on a study by Forrester Research at the beginning of last year (2009) noting the differences in costs:

For typical information workers, Forrester estimates that it costs a company $25.18 per user per month for an on-premise e-mail system, including the hardware, labor and other costs associated with managing e-mail in-house. Alternatively, for companies using Google’s fully Web-based Gmail, it costs a mere $8.47. Microsoft Exchange Online, Microsoft’s version of a fully cloud-based e-mail, isn’t quite as cheap as Gmail but rings in at $20.32 per user per month.

The cost calculations in the Forrester study were based on examining 53 enterprise-sized companies, that means BIG organizations. According to Jason Hiner of TechRepublic.com the cost difference to an organization of 100 people is even more staggering:

Google charges its Premium customers $50 per user per year. Even hosted Exchange plans cost about $500 per month plus about $6 per user per month. For a smaller company with just 100 users that would make the cost of Google Apps Premium $5,000/year vs. $13,200/year for the hosted Exchange solution. And an in-house Exchange solution will typically have a total cost of ownership (TCO) that is even higher than the hosted solution.

For non-profits the savings is even larger as Google offers a non-profit rate of a mere $30 per user per year. And for those small businesses content to make due without the larger mailboxes (you’ll have to settle for only 7GB), enterprise options, and support guarantees that come with Google Apps Enterprise Edition, the Standard Edition’s cost of $0—that’s zilch, zero, nada—is unbeatable.

One of the biggest, if not the biggest reason that organizations aren’t switching to Gmail is the reluctance to train employees who have grown used to Outlook to use Gmail. Those of us used to using Gmail and its incredible interface could simply dismiss this as a silly reason to continue paying through the nose for email, but organizational fallout over a software switch is a real thing to consider and shouldn’t be dismissed out of hand.

Thankfully, using Google Apps as an alternative to running costly Exchange servers doesn’t mean that users have to immediately abandon their beloved Outlook. Gmail supports both IMAP and POP3 mail protocols, so that Outlook can continue to be used as an email client. This way, organizations can slowly introduce Gmail’s other features to users, perhaps by making the web interface the only way to access email on a non-work machine, like how many companies currently use Microsoft’s Outlook Web Access solution.