It certainly can work - especially if the emails are highly-targeted and personalized. The best case is the prospect responds and a sale is generated. The worst case is they respond and ask to not be contacted again. For everyone else, you now have a targeted prospect to either follow up with through another email or any other means. Email marketing can supplement any marketing strategy (and can drive website traffic).
I do not use a program. They are all personalized emails that are sent out individually. I include an opt-out message; so if that prospect doesn't want to hear from me again, I make the adjustment immediately.
It is ideal if your product/service has a broad geographic reach. It is also ideal if the customer is a medium to large business. We can discuss this and I will certainly let you know if I don't think I would be able to add value for you.
We would work on that together, and you would always have full control of what goes out and when it goes out. After I learn about your product/service, I come up with an initial draft for your review. You would then edit the message to ensure it fits your marketing strategy. I try to keep the emails concise with a compelling subject line in order to facilitate a higher reach.