I've been testing multiple email headlines for some time now and below headlines had the highest open rate:
1- You Will Love This... (20% on average)
2- How I (Insert Benefit) In Record Time... (17% on average)
3- Seven Deadly [blank] Mistakes (16% on average)
4- Discover the 'Insider' Strategies That... (13% on average)
Any one want to share some of their best converting email subjects?