If anyone tries to sell you a service for global email marketing or the like, it's probably spam on a horrific scale, and spam won't make you any friends at all, let alone contented readers. But there are useful promotional steps you can take without alienating everyone, so read on.
Pricing is a major promotional tool. Data seems to show that $2.99-$4.99 is the sweet spot for maximising ebook income, but new epubbers need to build a following of readers first before even thinking about income. And in that case the fantastic flexibility of epubbing comes into its own, as you can move prices up and down to find what works best for you. (Apple insists on book prices ending in .99, so that's become the standard.) Below $2.99 Amazon and Barnes & Noble keep a larger percentage of the sale, so again, $2.99 is a popular cutoff point.
Smashwords provides a coupon system so you can set a book's price at zero if you want to distribute it to certain groups, or simply give a boost to uptake. Many authors price the first book in a series at zero, then once they build up a reading public the can charge more for later volumes in the series. There are whole strategies around maintaining a zero price on Amazon, so search for 'perma-free' for find out more.
Here's a great article by David Gaughran on pricing, and
another by Mark Coker, whose Smashwords blog has provided an amazing
amount of useful information over the years. And more information on ebook
marketing from David Gaughran, and the Marketing Onion.
The channels information from the Pathways and Details pages has been summarised in one printable pdf file, which appears with many other useful links on 9. Resources.