2025 Email Marketing Benchmark Report

At Contact Fuel, we know that email deliverability is the backbone of digital marketing success. Even the best creative campaigns fail if emails don’t land in the inbox. That’s why benchmark reports are so valuable—they help marketers measure their performance against industry standards and spot issues before they become serious.

Postmastery recently released its Q2 2025 Email Delivery Benchmark Report, analyzing billions of emails across major mailbox providers from April to June 2025. This edition offers the most robust data yet, thanks to an expanded sender cohort.

We’ve summarized the highlights below. For a deeper dive, you can download the full report here:
👉 Download the Postmastery Q2 2025 Benchmark Report

Key Findings from Q2 2025

1. Delivery and Bounce Rates Remain Strong (With Some Exceptions)

Most major mailbox providers reported delivery rates above 99%, but results varied. Seznam and BTInternet performed exceptionally well, while Mimecast and Comcast struggled with lower delivery and higher bounce/deferred rates.

2. Microsoft Tightens Authentication Requirements

Microsoft (Outlook, Hotmail, Office365) now requires both SPF and DKIM to pass and align, exceeding DMARC standards. This has led to increased DKIM-related bounces, even when DMARC passes. Senders must carefully audit their authentication setup.

3. Deferrals Point to List Quality Issues

Google, Yahoo, and iCloud often deferred emails when users received too many messages too quickly. This can be a sign of poor list practices or bot-driven list attacks. Persistent deferrals should be treated as hard bounces to protect reputation.

4. Spam Complaint Thresholds Are Shrinking

Orange is reducing its acceptable spam complaint threshold to 0.3% starting mid-August 2025. Anything higher could trigger filters, putting more pressure on senders to improve relevance and engagement.

5. Major Ecosystem Changes

• AT&T domains are migrating to Yahoo Mail, meaning Yahoo’s filtering rules now apply.
• Orange Spain will shut down all email services permanently as of September 5, 2025.

6. Delivery Speed Matters

BTInternet and GMX had the fastest delivery times (often under 30 seconds), while Google, Outlook, and Yahoo averaged 3–5 minutes. Comcast lagged significantly, sometimes taking over an hour.

What Businesses Should Do Now

1. Benchmark your results against provider-specific data.
2. Audit authentication—SPF, DKIM, DMARC alignment is critical for Microsoft domains.
3. Lower complaint rates—aim for well below 0.3%.
4. Track ecosystem shifts like AT&T → Yahoo and Orange Spain shutdown.
5. Continuously audit infrastructure—including DNS reliability and feedback loops.