Open Rates

What is email open rate? What exactly counts as an open? How is open rate calculated? How does the tracking-pixel mechanism work? How does Apple Mail Privacy Protection (MPP) affect open rate accuracy? How does Apple Mail Privacy Protection (MPP) inflate open rates? Is open rate still a useful metric? How can I estimate real open rates with MPP? What are email image proxies (e.g., Gmail Image Proxy)? How do image proxies affect open tracking? How does proxy caching distort open rates? Why do Gmail and Outlook handle images differently? What is the difference between unique and total opens? What is an “open time” and how accurate is it? Why do some contacts show 0 opens when they actually read the email? Why do test addresses or internal opens skew data? What’s a realistic benchmark for open rates by industry? Should open rate still be used as a KPI? How do bots and link scanners inflate open counts? What’s the difference between “opened” and “viewed” in different ESPs? What are open-rate deltas between transactional and marketing emails? What is a pixel block and how do privacy settings affect it? How can I improve my open rates?