I have spam this morning from some internet service (addressed to "liz at elizabethbear dot com"--which is one of those email addresses that only exist because anything at elizabethbear dot com gets dumped into my mailbox--and the only people who actually know me who call me "Liz" are scott_lynch and guipago, and they only get away with it because Scott is bigger than I am and Jenny is too cute to hit, so I have capitulated.... ) which is offering "...currently allowing writers that receive this email to use its email query service for 50% OFF. They send your manuscript description addressed BY INDIVIDUAL NAME to well over a thousand publishers and literary agents."
So, in other words, they'll use a bulkmail protocol to send your untailored query to a whole bunch of people who will roll their eyes and delete it. Do I need to explain why this is a bad idea, or can everybody pretty much do the math their own self?
Generally speaking, when a reputable agent pitches a book to an editor, the agent, you know, knows something about what the editor is looking for and tailors the pitch. Generally speaking, when an unrepresented writer is seeking an agent (or going direct to a publisher) she tailors her query letter to that specific agent or publisher.
Generally speaking, people with a book in print at anything resembling a publishing house where they-pay-you-you-don't-pay-them aren't going to be interested in a bulk-mail e-query service. And I would normally think that this "50% off coupon" (for a service you don't want, trust me) is the result of a web spider looking for web pages with the word "writer" or "novel" on them and harvesting email addresses...
...except the email address on my web page is not "liz" at anything.
Anyway, if you get one of these, there are better things to waste your money on. Get a massage; it'll be better for your career in the long run.