1. Don't do it, this is very last decade thinking. 2. Think about your email reputation!!! Everytime you send our unsolicited emails your getting flagged as spam and taking not just you, your whole account, but anyone else who happens to share your sender address down with you. Rude! 3. It doesn't work. People don't engage with things they didn't initially request. There are super high unsubscribe rates for programs like this.
I find it to be much better to do 3rd party content distribution instead. Make some really great interesting piece of content, then provide it to others to provide to their contacts. You'll get more qualified leads than from purchasing a list.