<\/span><\/h2>\nThe research analysed hundreds of email lists across industries<\/strong>, including retail, finance, SaaS, and non\u2011profits, to measure how quickly email addresses become invalid or inactive. It was conducted by experts in email deliverability, data quality and customer engagement analytics.<\/p>\nThe study examined:<\/p>\n
\n- active engagement rates<\/li>\n
- email bounce rates<\/li>\n
- inactive or dormant addresses<\/li>\n
- changes in subscriber status over time<\/li>\n<\/ul>\n
<\/span>2. Key Finding: Rapid Decay Over Time<\/span><\/h2>\nThe most headline\u2011grabbing result is that email lists degrade quickly without regular maintenance<\/strong>:<\/p>\n\n- On average, 20\u201330% of email addresses become stale or invalid within 12 months<\/strong><\/li>\n
- After 2 years<\/strong>, nearly half (40\u201350%)<\/strong> of addresses can be inactive or undeliverable<\/li>\n
- Beyond 3 years<\/strong>, lists often contain 50%+ invalid addresses<\/strong><\/li>\n<\/ul>\n
This means that a list that\u2019s not cleaned regularly can become increasingly inefficient and costly. Older lists show higher bounce rates, lower open rates, and more negative signals (such as spam complaints).<\/p>\n
Analysts say the decay pattern is consistent across sectors \u2014 though the exact rates differ slightly depending on customer behaviour and industry.<\/p>\n
<\/span>3. Why Email Addresses Decay<\/span><\/h2>\nThere are several reasons email lists deteriorate:<\/p>\n
<\/span>A. People Change Email Addresses<\/span><\/h3>\n\n- job changes<\/li>\n
- switching to new providers<\/li>\n
- abandoning old accounts<\/li>\n<\/ul>\n
<\/span>B. Users Stop Engaging<\/span><\/h3>\nEven if the address is still valid, users may stop opening or clicking<\/strong>, leading to \u201cinactive\u201d status.<\/p>\n<\/span>C. Spam Traps and Role Accounts<\/span><\/h3>\nOld or unmanaged lists often contain:<\/p>\n
\n- spam trap addresses<\/strong> used by ISPs to catch poor list hygiene<\/li>\n
- role accounts<\/strong> (e.g., info@, support@) that don\u2019t belong to individuals<\/li>\n<\/ul>\n
<\/span>D. Data Errors and Typos<\/span><\/h3>\nIncorrectly entered addresses or outdated contact data accumulate over time without cleaning.<\/p>\n
<\/span>4. Impact on Deliverability and Performance<\/span><\/h2>\nMaintainers of email programs know that poor list health affects campaign effectiveness:<\/p>\n
\n- Higher bounce rates<\/strong> can lead mail servers to block sending domains<\/li>\n
- Low engagement<\/strong> hurts sender reputation with mailbox providers<\/li>\n
- Spam complaints<\/strong> increase when uninterested or outdated subscribers receive mail<\/li>\n<\/ul>\n
The study found that companies with neglected lists saw open rates drop by 15\u201330%<\/strong> and click\u2011through rates decline similarly within a year without cleaning.<\/p>\n<\/span>5. Industry Benchmarks and Engagement Trends<\/span><\/h2>\nThe report offered benchmarks showing how engagement erodes:<\/p>\n
\n- Active openers:<\/strong> fall by ~10\u201315% in the first 6 months without re\u2011engagement efforts<\/li>\n
- Bounce rates:<\/strong> rise by 5\u20137 percentage points year over year if lists aren\u2019t cleaned<\/li>\n
- Inactive segments:<\/strong> typically make up the largest share of unengaged contacts<\/li>\n<\/ul>\n
<\/span>6. Methodology<\/span><\/h2>\nResearchers used a mix of:<\/p>\n