Nearly 18% of emails never reach the inbox, and for most organizations, that silent failure is costing them up to a fifth of their potential email ROI. That is the central finding from the Sinch Mailgun Email Impact Report 2026, published on April 8, 2026, which draws on one of the most comprehensive datasets in the industry's recent history.
The report combines insights from more than 400 billion emails sent in 2025 and a global survey of over 1,200 email senders, making it a significant reference point for any team managing email at scale. While 78% of respondents say email is critical to business success, the research also highlights a growing disconnect between performance and execution, driven by gaps in measurement, deliverability practices, and AI application.
A Deliverability Problem with a Real Price Tag
The stakes here are not abstract. Email marketing generates between $36 and $40 for every dollar spent, a return that outperforms most other marketing channels by a significant margin. When nearly one in five messages never lands in an inbox, that revenue potential shrinks before a single open or click can happen.
The deliverability problem is broader than many senders realize. According to Validity's 2025 Benchmark Report, the global average inbox placement rate is 83.5%, meaning roughly 1 in 6 legitimate marketing emails is never seen. The Sinch Mailgun data pushes that failure rate even higher. Meanwhile, Gmail and Yahoo now mandate SPF, DKIM, and DMARC authentication for bulk senders transmitting over 5,000 messages per day, meaning the minimum bar for even reaching the inbox has risen sharply in recent years.
The Sinch Mailgun survey included users of Sinch email brands, specifically Mailgun, Mailjet, and Email on Acid, as well as a custom panel of high-volume senders across the U.S., UK, France, Germany, and Spain. Of the 1,234 total respondents, 769 were Sinch customers alongside other participants from the email community. The survey was fielded from late September through early November 2025.
