An analysis of 85,637 email campaigns from Mixpanel, involving 1.7 billion emails sent between June 2012 and May 2016, reveals insights into factors influencing email open rates. The overall open rate was 13.53%, with campaigns featuring shorter subject lines under 40 characters performing better, achieving a 15.05% open rate. Personalization, such as including the recipient's name, showed a lower open rate of 9.34%, while polite language like "please" or "thank you" resulted in a significant increase to 22.98%. Urgency-inducing words like "today" and "now" did not notably improve open rates, and although promotional terms like "sale" and "offer" had an open rate of 10.34%, using "free" surprisingly increased it to 17.27%. Smaller, targeted campaigns had higher open rates compared to large mass emails. This study suggests questioning outdated best practices, as the effectiveness of email marketing strategies evolves with changing email reading behaviors.