• by Ray Schultz , Columnist, 8 hours ago

Email remains a powerful and cost-effective medium. But global volume declined last year for the first time in the history of Validity’s annual Delivery Benchmark report. 

“In 2025, average sending volume fell between March and April, then stayed subdued through summer in the Northern hemisphere,” Validity writes in its 2026 report, which appeared on Wednesday.  “This slowdown started when Yahoo began enforcing new bulk sender requirements and Microsoft introduced new requirements with immediate enforcement. Sending volumes then followed their typical pattern, spiking during the Q4 holiday sales season.” 

AI may also have helped marketers send smaller, more targeted campaigns. This, in turn, helped them create more relevant emails. Spam complaints trended downwards, even during the holiday season.

“Overall, the average global inbox placement rate was 87.2%--a 3.7% uplift year over year,” the study adds.   

“Over the past two years, Gmail, Yahoo, and Microsoft introduced mandatory guidelines for high-volume email senders,” it continues. “These requirements include DMARC authentication, one-click unsubscribe options, and low spam complaints. While long considered best practies, making them mandatory has improved subscriber trust, engagement, and yes, deliverability. Microsoft’s rollout explains the upswing we see from Q1-!2 –already-compliant senders benefitted as Microsoft recognized their DMARC status.”

The year 2025 also saw a decline in email rejected rates. 

“Rejected rates were below average for most of the year, reflecting senders’ awareness of (and compliance with) Yahoo, Gmail, and Microsoft’s bulk sender requirements, the study continues.

“However, during the high-pressure holiday sales season, rejection rates spiked as senders ramped up email volume in an effort to meet revenue goals.” 

As it stands, Microsoft is still the toughest MBP service to send to, with a 77.4 inbox placement rate. 

And there was one new wrinkle in the relationship with the sending platforms. 

“Mailbox providers are prioritizing user engagement as a primary trust signal--and brands that don’t adapt their strategies risk losing inbox visibility,” Validity writes. 

And keep this in mind: “While guidance over the years told senders to keep their spam complaint rates below 0.2-0.3%, under 0.1% is now the expectation.” 

And hard bounces, or unknown users, as Validity calls them? They stayed flat through the year. One reason was the new bulk sender guidelines from mailbox providers.  

In addition, senders “focused more on email address quality, validating new addresses at the point of collection and throughout the subscriber lifecycle--meaning fewer bounces.”  

But be advised that “MBPs close inactive email accounts--Yahoo after 12 months and Gmail after 24 months--meaning bounces are more likely when mailing to older lists.”

Validity acknowledges that this study is a snapshot in time. The analysis is based on client activity. spam rates, deliverability rates and other types of data aggregated into Validity’s Mailbox Provider Community. Validity excludes senders who have not approved for their data to be aggregated for this purpose.