TCO - with the emphasis on 'Total'

The TCO (Total Cost of Ownership) of your IT equipment should be calculated so as to include the skills of any resource required to keep it up and running. If you leave this out then it is only PCO, partial cost of ownership.

If you run your email on an internal Exchange server or similar system then you need to factor in the cost of having those skills on hand. Emergencies can and will happen as this recent post on the tech website 'The Register' shows. http://www.theregister.co.uk/2011/06/18/microsoft_exchange_eseutil_recovery/

Email downtime is a terrible thing and can have a real impact on business, especially those involving multiple locations. Whilst web based email solutions aren't perfect, Google has an uptime for Gmail of 99.99% and proudly boasts 0% planned maintenance.

The skills required to administer and maintain Microsoft's Exchange Server don't come cheap, and are even more expensive if you have to buy them in to fix a specific problem on an ad-hoc basis.

Have you thought about how your organisation would function without its email systems for a day? or a week?

So when your current email system is up for replacement or upgrade remember to factor in the costs of the skills required to keep it up and running. Google provides a rough and ready cost comparison tool here. All figures are in $ but just substitute your local currency of choice and it will give you a close estimate.