30 Email Deliverability Tool Statistics That E-commerce Brands Need to Know in 2025

Data-driven analysis revealing the state of inbox placement and how specialized tools are transforming email marketing ROI for online retailers

Email remains the highest-ROI channel for e-commerce brands, yet 16.9% of marketing emails never reach the intended recipient's inbox. This massive gap between emails sent and emails seen represents billions in lost revenue annually. While traditional deliverability solutions require months of content changes and technical overhauls, Mailmend's placement technology moves campaigns from Gmail's Promotions tab to the Primary inbox on Day 1—without changing a single word of email content.

Key Takeaways

• The deliverability crisis is accelerating — Major ESPs experienced inbox placement declines of 13-28% year-over-year in Q1 2025

• Market demand is surging — The email deliverability tools market will reach $2.41 billion by 2032, growing at 9.1% CAGR

• Email ROI remains unmatched — Brands generate $40 for every $1 spent on email marketing when messages reach the inbox

• Speed matters more than ever — Mailmend clients achieve 112% revenue increases within 24 hours of implementation

• Most marketers acknowledge the problem — 61% of email marketers believe deliverability is getting harder each year

• High-volume senders face the steepest declines — Brands sending 1M+ emails monthly saw deliverability drop 22.35% in the past year

Understanding Email Deliverability Challenges and Solutions

1. 16.9% of all marketing emails never reach the inbox

Nearly 1 in 6 marketing emails fail to reach recipients, disappearing into spam folders or vanishing entirely. This baseline metric represents the fundamental challenge facing every e-commerce brand relying on email for revenue. The gap between "sent" and "delivered to inbox" costs retailers millions in unrealized sales.

2. Average email deliverability across 15 ESPs sits at just 83.1%

Testing across major email service providers reveals an average deliverability rate of 83.1% in 2024. This means even well-configured accounts lose roughly 17% of their messages before recipients ever see them. For e-commerce brands sending promotional campaigns, actual Primary inbox placement rates are often far lower.

3. 10.5% of emails land in spam folders

Beyond complete delivery failures, 10.5% of emails end up in spam folders where they're virtually invisible to recipients. Spam folder placement destroys open rates and makes every campaign substantially less profitable. This percentage doesn't include emails routed to Gmail's Promotions tab, which further reduces visibility.

4. 6.4% of emails go missing entirely

A significant 6.4% of emails simply disappear—never delivered, never bounced, never seen. These "undelivered" messages represent a complete loss of marketing investment with zero chance of generating revenue.

5. The email deliverability tools market reached $1.2 billion in 2024

Global investment in deliverability solutions hit $1.2 billion in 2024, reflecting the critical importance of inbox placement for digital commerce. This market size demonstrates that businesses recognize deliverability as a core revenue driver rather than a technical afterthought.

6. Market projected to reach $2.41 billion by 2032

The deliverability tools market is forecast to more than double, reaching $2.41 billion by 2032. This growth trajectory indicates that inbox placement challenges will intensify, making specialized tools essential for competitive e-commerce operations.

7. 9.1% CAGR growth rate from 2025 to 2032

The market's 9.1% growth rate outpaces overall digital marketing spending, signaling that brands are prioritizing deliverability investments over other channels. This sustained growth reflects the direct connection between inbox placement and revenue.

The Importance of an Email Deliverability Test

8. Daily email volume reached 347.3 billion in 2023

The sheer scale of email traffic—347.3 billion daily messages in 2023—means inbox providers use increasingly sophisticated filtering. Testing before sending ensures campaigns clear these filters rather than getting lost in the noise.

9. Email volume projected to hit 361.6 billion daily in 2024

Growing to 361.6 billion daily emails in 2024, the competition for inbox attention intensifies each year. Pre-send testing becomes more critical as mailbox providers tighten filtering to protect users from message overload.

10. 61% of email marketers believe deliverability is getting harder

A majority of marketers—61%—report that achieving inbox placement has become more difficult. This professional consensus confirms that historical strategies no longer work and specialized testing tools are now essential.

Evaluating Email Delivery Tools for E-commerce Success

11. 81% of small businesses depend on email for customer acquisition

For smaller e-commerce brands, email is the primary growth engine—81% rely on it for customer acquisition. When deliverability fails, these businesses lose their most cost-effective channel for reaching new customers.

12. 80% of small businesses use email for customer retention

Beyond acquisition, 80% of SMBs depend on email for retention marketing. Repeat purchases drive e-commerce profitability, making inbox placement essential for sustainable growth.

13. Email marketing yields $40 ROI for every $1 spent

The unmatched $40 return for every dollar invested in email marketing makes deliverability optimization one of the highest-leverage activities available. However, this ROI assumes messages actually reach the Primary inbox where recipients engage with them.

14. North America holds 34% of the deliverability tools market

The 34% market share in North America reflects the region's mature e-commerce ecosystem and sophisticated understanding of deliverability's revenue impact. Brands in this market increasingly treat deliverability as a competitive advantage rather than a technical checkbox.

How a Mail Tester Identifies Inbox Placement Issues

15. Klaviyo's inbox rate dropped 13.24% year-over-year

Even the e-commerce industry's preferred ESP saw deliverability decline from 56.90% to 43.66% between Q1 2024 and Q1 2025. This drop affects every brand using the platform, regardless of their individual sending practices.

16. Mailgun experienced the steepest decline at 27.75%

The largest year-over-year drop came from Mailgun, falling from 53.80% to 26.05%. This dramatic decline demonstrates how quickly deliverability can deteriorate and why continuous monitoring matters.

17. MailChimp's inbox rate fell 19.63%

Another major platform saw substantial decline, with MailChimp dropping from 51.93% to 32.30%. Brands using shared sending infrastructure face compounding problems as platform-wide reputation suffers.

18. Amazon SES deliverability declined 14.60%

Even Amazon's infrastructure couldn't prevent a 14.60% decline in inbox placement. Technical sending capability alone doesn't guarantee Primary inbox delivery.

Standard mail testers identify spam triggers and authentication issues. Mailmend's proprietary AI goes further, analyzing the combined factors Gmail's algorithms use to categorize messages as promotional. This "promotional threshold" analysis generates account-specific custom code that moves emails to the Primary inbox—where Dr. Squatch achieved 112% revenue increase with 42% higher open rates and 67% CTR improvement within 24 hours of implementation.

Improving Your Email Reputation for Better Deliverability

19. Gmail's inbox rate decreased 5.02% to 53.70%

The world's largest email provider now places just 53.70% of messages in the inbox, down from 58.72% the previous year. This tightening affects every sender and makes reputation management increasingly important.

20. Office365 saw the biggest provider decline at 26.73%

Microsoft's business email platform implemented aggressive filtering, with inbox placement dropping from 77.43% to 50.70%. B2B e-commerce brands face particular challenges reaching corporate buyers.

21. Outlook inbox placement fell 22.56%

Consumer-facing Microsoft accounts similarly declined, falling from 49.33% to 26.77%. Multi-provider reputation management has become essential for comprehensive deliverability.

22. Google achieves 95.54% total deliverability (including Promotions tab)

Google's infrastructure delivers 95.54% of messages somewhere—but "somewhere" often means the Promotions tab where open rates plummet. The distinction between technical delivery and Primary inbox placement is critical for revenue.

Mailmend's "zero changes" approach improves effective email reputation through better placement rather than requiring content overhauls. Brands maintain aggressive promotional strategies while achieving Primary inbox visibility through Mailmend's algorithmic technology.

Understanding and Optimizing Your Sender Score

23. High-volume senders (1M+ emails/month) saw deliverability drop 22.35%

The largest senders faced the steepest decline, with inbox rates falling from 49.98% to 27.63%. Scale now works against deliverability, making optimization essential for growth-stage brands.

24. Mid-volume senders (200k-1M/month) actually improved 11.19%

Interestingly, moderate-volume senders saw rates increase from 49.77% to 60.96%. This suggests optimal sending ranges where list quality and engagement metrics align with provider preferences.

25. Low-volume senders (1-10k/month) improved slightly at 0.8%

Small senders maintained stability with minimal improvement from 49.40% to 50.20%. Lower volumes may avoid triggering aggressive filtering, though they also limit revenue potential.

Email Analytics: Measuring Your Deliverability Success

26. Dr. Squatch achieved 112% email revenue increase in 24 hours

The personal care brand's implementation of Mailmend delivered 112% revenue increase within one day, with 42% higher open rates and 67% CTR improvement. This dramatic improvement came purely from Primary inbox placement—without any changes to email content, copy, or sending strategy.

27. StickerYou recorded 20% Day 1 boost growing to 100% by month one

E-commerce brand StickerYou achieved a Day 1 boost of 20% with results growing to 100% increase by month one. The brand saw 64% higher open rates and 43% CTR improvement. Consistent Primary inbox placement creates cumulative performance gains.

28. Ministry of Supply saw results within one business day

The apparel brand experienced measurable improvement within one business day of Mailmend implementation, achieving 27% higher open rates and 30% CTR improvement, demonstrating the speed advantage of algorithmic solutions over traditional deliverability consulting.

29. Larsson & Jennings achieved 82% open rate increase

The watch brand saw 82% improvement in open rates with 51% CTR improvement through Primary inbox placement—with the solution "saving their Black Friday" after data failures had caused deliverability problems.

30. North America achieves 87.9% regional deliverability

The 87.9% average deliverability rate in North America exceeds global averages, yet still leaves substantial room for improvement. Brands achieving Primary inbox placement outperform this baseline significantly.

Frequently Asked Questions

How quickly can I see results from an email deliverability tool for my e-commerce brand?

Results timeline varies dramatically by solution type. Traditional deliverability consulting requires weeks or months of content changes, domain warming, and technical modifications. Mailmend's algorithmic approach delivers measurable results on Day 1, with brands like Dr. Squatch achieving 112% revenue increase within 24 hours and Ministry of Supply seeing improvement within one business day.

Does using an email deliverability tool require me to change my email content or sending strategy?

Most deliverability solutions require substantial content modifications to avoid spam triggers and promotional categorization. Mailmend's "zero changes" approach works at the technical/header level rather than message content level, meaning brands maintain existing email copy, design, and sending frequency while achieving Primary inbox placement.

What is the "promotional threshold" and how does it affect my email campaigns?

Gmail's algorithms evaluate multiple factors to categorize messages as promotional, including sender patterns, content signals, and technical headers. When combined factors exceed the promotional threshold, emails route to the Promotions tab where visibility drops significantly. Mailmend's AI analyzes these factors and generates custom code that counteracts promotional categorization signals for each specific Klaviyo account.

How do email deliverability tools impact my overall email marketing ROI?

Email marketing yields $40 for every $1 spent when messages reach the Primary inbox. With 16.9% of emails never reaching recipients and many more landing in Promotions tabs, deliverability tools directly recover this lost potential. Mailmend clients consistently report 50-112% revenue increases from improved placement.

Is an email deliverability tool compatible with all email service providers (ESPs)?

Tool compatibility varies significantly. Generic deliverability testing tools work across platforms, but advanced placement optimization often requires specific ESP integration. Mailmend integrates exclusively with Klaviyo—the dominant ESP for e-commerce—providing native A/B testing, analytics integration, and drag-and-drop implementation in under 5 minutes.