Subject lines covered in the video:
1. The referral or fake referral
You can use linkedin or interviews they've done and call them out in the subject line to make them open the emails. A Good example is "Hey Mark - found you through Tim Ferriss"
2. Congrats on the News item
Google around and find recent work completed by the target, new hires or announcements of funding. "Hey Mark - great article on ecommerce optimization"
3. Generic but customized
Use this one if you can't find that much information on the target. The example in the video is "Hey Mark - about <Company> and InspireBeats"
4. Fully generic
Finally if there's no info on the company or you're too lazy to do the research, you can go full generic with a subject line like "Hi from Alex" or "Quick Question"