For any author, whether self-, small press-, or big house-published, getting noticed is one of the primary challenges. Larger publishers provide marketing support for their authors (yes, they really do, despite popular wisdom to the contrary), but with smaller publishers, and if you've self-published, you may be mostly or entirely on your own.
It's no wonder that the Internet is bursting with promotional services, marketing companies, publicity gurus, and book promotion self-help advice from authors who've been there, done that. Options range from staggeringly expensive (a good publicist can run you five figures) and rapaciously overpriced (AuthorHouse's Trifecta Review Service charges $3,000 for a set of reviews that would cost you around $1,200 if you purchased them separately yourself), to free (social media); and from helpful (the growing army of book bloggers), to dubiously effective (press releases, to which no one paid much attention even before the book market became so crowded, and vanity radio, which is likely to reach only a tiny audience), to simply absurd (such as Outskirts Press's Celebrity Endorsement Option, where you pay $109 to obtain contact information for 5 celebrities of your choosing, who will then ignore you).
Then there's the old standby, the email campaign. There's any number of email blast companies online, and many self-publishing companies also sell email services--for instance, Xlibris's email marketing campaigns, which range from $349 for a multi-author campaign and 200,000 addresses, to a jaw-dropping $9,996 for a "personalized" campaign and 10,000,000 addresses.
Targeted email blasts can be a useful publicity tool--as long as they really are targeted. For example, see author Michelle Dunn's tips for a successful email blast, which involves a list of addresses she built herself.
But most of the email campaign services you're likely to encounter are not targeted, despite what they may promise. (Common sense should tell you this in some cases--if the service promises to blast an email to 1,000 book reviewers, it's highly unlikely that there are anywhere near that many who'll be appropriate for any given book, since most reviewers specialize in particular genres or areas of interest.) Chances are that the addresses have simply been harvested from the internet--perhaps with some rudimentary filter, like "book reviewers," perhaps at random. And don't believe a claim that a service's mailing list is "opt in" (like this one from notorious "marketing" spammer BookWhirl) and therefore recipients are more likely to pay attention to the service's promotions. It probably just means that people have been added and haven't bothered to opt out.
Most email campaign services, in other words, are the equivalent of dropping your book announcement off the top of a building, and hoping it lands in front of someone who might be interested.
Case in point: the promotional email I received this week for a book titled JIHAD’S NEW HEARTLANDS - Why The West Has Failed To Contain Islamic Fundamentalism, published by AuthorHouse (the email was signed by an AuthorHouse "Marketing Advisor"). Even assuming that I paid attention to spammed book announcements (which I don't), I am a completely inappropriate recipient for this email. There's nothing whatever in any of my various online profiles or my Internet activity to suggest I have a particular interest in Islamic fundamentalism, or even the Middle East--and if I was being approached as a reviewer, rather than a reader, not only have I not reviewed in several years, but when I did review, I specialized in speculative fiction. Nor have I ever opted in to any commercial email lists--so if AuthorHouse sold this service to the author as an opt-in email campaign, they exaggerated just a tad.
So, writer beware: if you buy an email campaign, it's very likely that the emails will be going not to a selective list of individuals who are willing to receive commercial messages, but mainly to people like me, who have absolutely no interest in your book, and even less in being spammed (that is, if we even see the email before our spam filters dispatch it to oblivion). In other words, not a very good use of your marketing dollar.