Run your own server? You got to be kidding with advice like this. It is simple enough to get such a server up and operational. But, the maintenance effort needed on that server quickly outweighs any benefits. Ensuring the server has appropriate spam / virus protections, keeping these up to date, dealing with blacklistings, etc. It just is not worth it unless it is your job to maintain a server like this. If this is NOT your job, that job will suffer due to less time being available while you deal with email server maintenance.
In the end, it is much better to ask yourself two simple questions - How many mail boxes do I need? and How much storage is needed for each mail box? Using that information you can shop around and find a suitable solution where it is someone else's business to do that server maintenance. Prices and capabilities vary. Places like Rackspace offers an email services only option that costs much less than the time needed to host your own server. Gmail and the ilk become options as well. I hesitate to use the "free" services from companies like Google though - it is bad enough that I am relinquishing control of an essential service, I want to know that I am getting what I pay for. The contracts for free services are rather one sided with limited liabilities, IMO.