Buy leads from a lead selling site. These are supposed to be email addresses of people that have signed up to receive offers. You just have to watch that they have good fresh "double opting" leads of people who requested more information about your particular field or you could be marked as a spammer. Some of these sites will email them for you with your own email or you can buy separate leads and use a separate email site for the mailing. There are email programs you can use but then you have a problem that Internet providers usually only allow up to 500 emails per day, and if you're doing it every day they might (rightfully) accuse you of spamming and shut down your connection.
Firstly, a disclaimer – don’t spam Reddit and other similar sites hoping to “hit the jackpot” of referral traffic, because it’s not going to happen. Members of communities like Reddit are extraordinarily savvy to spam disguised as legitimate links, but every now and again, it doesn’t hurt to submit links that these audiences will find genuinely useful. Choose a relevant subreddit, submit your content, then watch the traffic pour in.
Brian, great post as always! Question: Do you consider authority sites (industry portals) a form of “influencer marketing?” e.g. guest blogging, etc? In some niches there are not so many individuals who are influencers (outside of journalists) but there are sites that those in the industry respect. I am in the digital video space and for me one site is actually a magazine that is building a very strong digital presence. Thanks, keep up the good work!