I know google hires some people who are better than me, but that doesn't mean the gmail system is better than something I could engineer.... For one thing, google needs to have a much lower cost per user than I do, forcing them to make some choices that I don't have to. I have no problem paying $50 a month for email service, and that level of cost per user would be untenable on a free email service. (I host most of my email myself, and I'm trading a free co-lo to mark perkel of junkemailfilter.com to do my filtering. between that and my time, I'd guess $50/month)

This is true, but also very unfortunate, as GMail is often a poor substitute for a well-administered in-house e-mail system.

Running a mail system for 10 people is a lot easier than running one for a few million.