Have you ever, for any reason, answered a marketing/sales email from a sender you did not personally recognize?
I get about 6-10 of the, "Hi, I'm a web developer that can improve your site" emails every single day. Some better crafted than others...
If you think such a campaign will be fruitful, I'd reconsider. If there were to be any chance of hitting someone actually willing to respond, one would need to send hundreds, if not thousands, of emails in hopes of a 0.01% response rate. The more "internet aware" the targets, the lower the response rate will be.
Perhaps it is merely my opinion, but I find such campaigns nothing but a waste of time - both on the part of the seller and for the prospective client.
"Spam" or unsolicited sales emails really only work when there is product to be sold which may gain the target's interest, or the target is already familiar with the seller - i.e. Amazon sending spam about latest deals.