When an email's file size exceeds 102KB, Gmail "clips" it, hiding the full message behind a link. Because the open-tracking pixel is typically in the email's footer, it doesn't load when a clipped message is opened, leading to severe under-reporting of your actual open rates.

Email providers prioritize senders with high engagement. Sending at least five emails per month generates more opens and clicks, signaling credibility. This counterintuitively leads to higher average open rates and better inbox placement, contrary to the common fear of over-sending.

Contrary to the fear of over-sending, emailing at least five times per month improves deliverability. Email providers view consistent recipient engagement (opens, clicks) as a sign of a credible sender, leading to better inbox placement and significantly higher open rates.

Open rates are unreliable due to automated actions, particularly Apple's Mail Privacy Protection (iOS 15+) which pre-fetches content and marks emails as opened without user interaction. Focus on metrics that reflect true intent, like clicks or conversions influenced by the subject line alone.

Many marketers track delivery rate, which only confirms a mail server accepted the email. True success lies in deliverability—the art and science of landing in the primary inbox, not the spam folder. This is an untrackable metric that you can only influence.

"Deliverability" simply means an email reached the mailbox, not the inbox. Actual inbox placement averages 83.5%, so it's normal for about one in six emails to land in junk or spam folders. This data helps marketing teams set realistic internal expectations.

Email Service Providers (ESPs) use proprietary algorithms to filter bot activity, leading to inconsistent and often inflated open/click metrics. Comparing performance across newsletters using different ESPs is like comparing apples to oranges, making the data misleading for marketers.

Tracking pixels used for open rates harm email deliverability and can get your domain flagged as spam. While useful for marketing A/B tests, sales teams focused on getting replies should disable tracking entirely. This maximizes the chance of landing in the primary inbox and appears more authentic to both filters and recipients.

Despite claims that Apple's privacy changes and bots have made them irrelevant, open rates remain a valuable leading indicator for email performance. Marketers who dismiss them are ignoring a crucial signal of audience engagement and list health. These metrics are provided by platforms and should be monitored.