Resources/Glossary/Cold email and lead gen
Open rate is the share of delivered emails that were opened. It has become unreliable since Apple Mail began loading email images in the background, which counts many emails as opened that nobody actually read.
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The share of delivered emails that were opened. It is unreliable since Apple Mail began preloading images, which counts many emails as opened that nobody read.
Open tracking works by placing a tiny invisible image in each email. When the image loads, the tool records an open. That method was never perfect, since some email apps block images by default and others load them automatically. Security scanners at many companies also open links and images automatically to check them for threats, which adds even more false opens.
Apple’s Mail Privacy Protection, introduced in 2021, made the problem much bigger. When it is on, Apple Mail downloads remote content in the background whether or not the person opens the email. Senders see an open that may never have happened. Tracking pixels and the custom tracking domains they use can also hurt deliverability on cold email, which is why many cold outreach teams switch open tracking off entirely.
Formula: Open rate = emails recorded as opened ÷ emails delivered × 100
Recruiters and agency owners still see open rates in their outreach tools and are tempted to judge messages by them. That leads to bad decisions, such as rewriting a subject line that was fine or calling contacts who only appeared to open. Replies, positive replies and meetings booked are far more honest measures of whether outreach works.
Two subject lines go to 200 candidates each in a recruiter's test. Version A shows a 68% open rate and version B shows 52%, so she nearly picks A. Then she checks replies: A got six and B got 14. Many of the opens on A came from Apple Mail users whose email apps loaded the images automatically. She keeps B and stops using opens to judge tests.
A few of the outreach tools in our directory, including our picks. Prices are the published starting price on the date we last checked.
With privacy features inflating opens, open rate is no longer a reliable measure of interest, so comparing it against benchmarks tells you little. Focus on reply rate and meetings booked instead.
Usually because Apple Mail Privacy Protection and some security scanners load images automatically, which records an open whether or not anyone read the email.
Many teams do. Tracking pixels add little useful data now and can slightly hurt deliverability. Tracking replies is simpler and more accurate.
Written by recruiters at Work Insiders. Part of the recruiting and HR tech glossary. Updated October 2026.
