New Email Impact Report 2026: 18% of Emails Miss the Inbox
Sinch Mailgun's new 2026 report reveals 18% of emails fail to reach the inbox. See why AI strategy and deliverability matter more than content generation.
New Email Impact Report 2026: 18% of Emails Miss the Inbox
Sinch Mailgun's new 2026 report reveals 18% of emails fail to reach the inbox. See why AI strategy and deliverability matter more than content generation.
Nearly 18% of emails never reach the inbox, putting up to a fifth of potential ROI at risk for the organizations sending them. That is the headline finding from the Sinch Mailgun Email Impact Report 2026, published April 8, 2026. The report introduces new industry benchmarks across 10 high-volume sending sectors, drawing on data from over 400 billion emails sent in 2025 and a global survey of more than 1,200 email senders. For marketers and growth teams who rely on email as a primary revenue channel, the numbers reveal a costly gap between what email can deliver and what most programs actually achieve.
The Inbox Problem Is a Revenue Problem
While 78% of respondents say email is critical to business success, the research highlights a growing disconnect between performance and execution, driven by gaps in measurement, deliverability practices, and AI application. Put simply: most teams believe in email, but a significant share are not running it effectively enough to capture its full return.
Fewer than half of organizations can accurately track their email program's ROI, and the gap between email's demonstrated potential and actual execution contributes directly to revenue losses. The deliverability problem makes this measurement gap worse. Nearly 18% of marketing emails never reach inboxes at all, which complicates the ability to measure ROI effectively, with up to one-fifth of potential returns at risk simply because messages are never seen.
This is not a trivial operational issue. Among organizations that do assess email ROI, 60% report returns exceeding $10 for every $1 spent, and more than 10% of companies claim returns as high as 40 times their investment. For teams leaving nearly one in five emails undelivered, those returns are being calculated on an incomplete picture.
What the Data Actually Shows
The survey covered users of Sinch email brands including Mailgun, Mailjet, and Email on Acid, as well as a custom panel of high-volume senders across the U.S., U.K., France, Germany, and Spain, with 1,234 total respondents.
Nearly 18% of emails never reach the inbox, putting up to a fifth of potential ROI at risk for the organizations sending them. That is the headline finding from the Sinch Mailgun Email Impact Report 2026, published April 8, 2026. The report introduces new industry benchmarks across 10 high-volume sending sectors, drawing on data from over 400 billion emails sent in 2025 and a global survey of more than 1,200 email senders. For marketers and growth teams who rely on email as a primary revenue channel, the numbers reveal a costly gap between what email can deliver and what most programs actually achieve.
The Inbox Problem Is a Revenue Problem
While 78% of respondents say email is critical to business success, the research highlights a growing disconnect between performance and execution, driven by gaps in measurement, deliverability practices, and AI application. Put simply: most teams believe in email, but a significant share are not running it effectively enough to capture its full return.
Fewer than half of organizations can accurately track their email program's ROI, and the gap between email's demonstrated potential and actual execution contributes directly to revenue losses. The deliverability problem makes this measurement gap worse. Nearly 18% of marketing emails never reach inboxes at all, which complicates the ability to measure ROI effectively, with up to one-fifth of potential returns at risk simply because messages are never seen.
This is not a trivial operational issue. Among organizations that do assess email ROI, 60% report returns exceeding $10 for every $1 spent, and more than 10% of companies claim returns as high as 40 times their investment. For teams leaving nearly one in five emails undelivered, those returns are being calculated on an incomplete picture.
What the Data Actually Shows
The survey covered users of Sinch email brands including Mailgun, Mailjet, and Email on Acid, as well as a custom panel of high-volume senders across the U.S., U.K., France, Germany, and Spain, with 1,234 total respondents.
The key findings paint a consistent picture:
60% of companies measuring email ROI report returns above $10 for every $1 spent, and more than 1 in 10 achieve returns as high as 40:1.
49% of respondents report improved email performance year-over-year, and 79% plan to maintain or increase their investment in email.
46% say AI improves speed and efficiency, while 41% of teams use AI to generate email content.
23% say AI has not improved their email programs at all.
The gap in AI results is one of the report's more actionable findings.
AI Is Being Used, But Not Where It Matters Most
AI adoption is widespread, but its impact remains uneven. Many teams focus on basic use cases such as content generation, while higher-impact applications such as optimization, segmentation, and deliverability remain underutilized.
Kate Nowrouzi, VP of Deliverability at Sinch, put it directly:
"Using AI to generate content is a good starting point, but it's not where the biggest impact happens. Organizations that apply AI to optimization, segmentation and deliverability are seeing stronger results."
Organizations that use AI more effectively are significantly more likely to report improved email performance. The implication for marketing teams is clear: deploying AI at the infrastructure and segmentation layer, not just to generate subject lines, is where the measurable lift comes from.
Deliverability Gaps Are Industry-Wide, Not Outliers
The 18% miss rate sits within a broader pattern of inbox placement challenges across the industry. According to Validity's 2024 Email Deliverability Benchmark, roughly one in six emails never reaches the inbox, keeping the global inbox placement average around 84%, even as mailbox providers enforce stricter authentication and engagement-based filtering.
Authentication gaps are a documented contributor. Only around 33.4% of top 1 million domains publish valid DMARC, and approximately 85.7% do not enforce it, leaving them vulnerable to spoofing and deliverability issues. Fully authenticated domains using DMARC are 2.7 times more likely to reach the recipient's inbox compared to unauthenticated domains.
Industry performance also varies sharply. Industries with opt-in friction, such as financial services and B2B SaaS, tend to sit above the median, while industries with aggressive acquisition tactics or high send volume, such as retail and eCommerce, tend to sit below.
What Marketers Should Take Away
The key findings paint a consistent picture:
60% of companies measuring email ROI report returns above $10 for every $1 spent, and more than 1 in 10 achieve returns as high as 40:1.
49% of respondents report improved email performance year-over-year, and 79% plan to maintain or increase their investment in email.
46% say AI improves speed and efficiency, while 41% of teams use AI to generate email content.
23% say AI has not improved their email programs at all.
The gap in AI results is one of the report's more actionable findings.
AI Is Being Used, But Not Where It Matters Most
AI adoption is widespread, but its impact remains uneven. Many teams focus on basic use cases such as content generation, while higher-impact applications such as optimization, segmentation, and deliverability remain underutilized.
Kate Nowrouzi, VP of Deliverability at Sinch, put it directly:
"Using AI to generate content is a good starting point, but it's not where the biggest impact happens. Organizations that apply AI to optimization, segmentation and deliverability are seeing stronger results."
Organizations that use AI more effectively are significantly more likely to report improved email performance. The implication for marketing teams is clear: deploying AI at the infrastructure and segmentation layer, not just to generate subject lines, is where the measurable lift comes from.
Deliverability Gaps Are Industry-Wide, Not Outliers
The 18% miss rate sits within a broader pattern of inbox placement challenges across the industry. According to Validity's 2024 Email Deliverability Benchmark, roughly one in six emails never reaches the inbox, keeping the global inbox placement average around 84%, even as mailbox providers enforce stricter authentication and engagement-based filtering.
Authentication gaps are a documented contributor. Only around 33.4% of top 1 million domains publish valid DMARC, and approximately 85.7% do not enforce it, leaving them vulnerable to spoofing and deliverability issues. Fully authenticated domains using DMARC are 2.7 times more likely to reach the recipient's inbox compared to unauthenticated domains.
Industry performance also varies sharply. Industries with opt-in friction, such as financial services and B2B SaaS, tend to sit above the median, while industries with aggressive acquisition tactics or high send volume, such as retail and eCommerce, tend to sit below.
What Marketers Should Take Away
The Sinch Mailgun report frames the core problem as an execution gap, not a channel problem. Email ROI holds up when programs are built correctly. The data shows that the teams reporting 40:1 returns are not using a different channel; they are measuring more carefully, authenticating properly, and applying AI where it improves targeting rather than just output speed.
As Kate Nowrouzi noted, "Email delivers exceptional returns, but many organizations are not set up to capture its full value," with the disconnect driven by gaps in measurement, deliverability practices, and AI application.
For business owners and growth teams, the immediate priorities are straightforward: audit inbox placement rates by sector, close authentication gaps with full SPF, DKIM, and DMARC enforcement, and shift AI investment toward segmentation and deliverability monitoring rather than content generation alone.
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The Sinch Mailgun report frames the core problem as an execution gap, not a channel problem. Email ROI holds up when programs are built correctly. The data shows that the teams reporting 40:1 returns are not using a different channel; they are measuring more carefully, authenticating properly, and applying AI where it improves targeting rather than just output speed.
As Kate Nowrouzi noted, "Email delivers exceptional returns, but many organizations are not set up to capture its full value," with the disconnect driven by gaps in measurement, deliverability practices, and AI application.
For business owners and growth teams, the immediate priorities are straightforward: audit inbox placement rates by sector, close authentication gaps with full SPF, DKIM, and DMARC enforcement, and shift AI investment toward segmentation and deliverability monitoring rather than content generation alone.
