Where do the Review My Emails calculator's numbers come from?
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The decay bands. No single study gives these numbers. They are our estimate from sources that each measure something else, so treat them as a careful guess, not a study result.
Business lists decay fastest because work addresses die when people change jobs. The median time with one employer in the US is 4.1 years (BLS, January 2026), and about 3.2% of US workers leave a job each month (BLS JOLTS, July 2026, preliminary).
Personal mailboxes fade more slowly, through abandonment. Google deletes accounts left unused for two years, and Microsoft closes them after two years. Yahoo stops delivering to a mailbox after 12 months. Domains lapse too, and take their addresses with them: 75.3% of .com and .net names were renewed in Q3 2025 (Verisign).
People also leave on purpose. Unsubscribes run about 0.2 to 0.3% per campaign (Klaviyo), or about 0.22% across Mailchimp users and 0.19% for ecommerce. As an upper limit only, paid newsletters lose 5.06% to 16.67% of paying readers a month (beehiiv, 2026).
The inbox figure. Validity measures inbox placement with seed addresses its customers use to test campaigns at hundreds of mailbox providers, counting only senders who agreed to share. In 2024 that was 83.5% inbox, 6.7% spam and 9.8% missing. For 2022 it was 84.8%. By provider in 2024: Gmail 87.2%, Yahoo and AOL 86.0%, Apple 76.3%, Microsoft 75.6%. This is seed panel data from marketing senders, not what every list gets. A real list mixes engaged and quiet people, so yours can land higher or lower.
Delivered is not inboxed. Email tools usually report delivery as sent minus bounced. With bounces around 1.5%, that often shows as about 98.5% delivered (Validity's illustration, not a measurement). In a survey of over 1,100 senders, only 12% could define delivery rate (Sinch Mailgun, 2025).
Opens and revenue. Apple's privacy opens passed 50% of all opens by May 2022 (Litmus), so opens alone overstate who is reading. Validity puts an inboxed marketing email at about $0.10 in revenue, a model rather than a measured study. Klaviyo reports about $0.11 in campaign revenue per recipient.
Curious what decay has done to your own list? Run the calculator, then clean your first 1,000 free at Review My Emails.
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