Ask HN: Can we monetize Twitter with DMs? Review PubliciTweet

We are in a beta period with PubliciTweet - http://publicitweet.com. The goal is to enable leveraging Twitter for marketing purposes. One key feature offered is the ability to send direct messages to all of your followers and track the success of the campaign both overall and per follower. We're aware that mass DMs are a spammers paradise. How can we target it more towards legitimate users (companies, musicians, etc)? What are your thoughts on the possibility of monetizing it by charging for using the service?