Hi Bobcat, if you're referring to Sitepoint's title, 'Create Stunning HTML Email That Just Works!', there are numerous mentions to using Campaign Monitor (http://www.campaignmonitor.com) to send and test your email newsletters. Alternately, you can look at using services like MailChimp, Constant Contact etc.
You do make an excellent point - there isn't a section in the book that explicitly tells the reader to use an email service provider. I'll raise this with the author (one of my colleagues) and see if it can be slipped into a future edition.
And no, sending HTML email via Outlook or Gmail won't work out, sorry. You really need to use an ESP to get this to work. Feel free to pop me a line if you have any questions