Source:Open Clip ArtUsing Under Public Domain Attribution

I have heard about a lot of email marketing. Some companies will give some rewards to anyone are happy to receive their marketing material. This way, the marketing material can go to a lot of different email box. My question will be about the quality of subscribers, not
quantity. Maybe, If I will give some rewards to some random people in the internet, I can be sure there will be a lot of people to join. That is a kind of Opt-in list, not just spam. That sounds great. The subscribers are possible to open and read, but they are doing only for getting the rewards. They may not pay any attentions to read those emails. They may not be my targeted customers at all!
Thus, we have to do in a smart way. There is a good example. My family joined a reward program of the department store which we did a lot of shopping. Every week, the store sent us some weekly special via email.A number of times, we came there because we found some things from their email. Moreover, they sent some discount vouchers to us via email, then we went there for using those vouchers. Well, end up, we bought somethings which we ever planned to buy from there .
The email marketing is sending the information to the people who are willing to read that.