1 The Zeigarnik Effect: Using subject lines that create an "Open Loop" in the reader’s mind—making it impossible for them not to click.
2 Social Proof & Reciprocity: Giving value first so the reader feels naturally inclined to engage with your brand.
3 Micro-Segmented Personalization: Making the reader feel like the email was written only for them, not a list of 10,000 people.