General Insights on Email Infrastructure and Deliverability
DKIM2: The Future of Email Authentication Is Taking Shape
2026/09/16 by Olivier Moulene.
The original DKIM specification has been a cornerstone of email authentication for more than a decade. However, real-world deployment has exposed fundamental limitations that persist even when layered with DMARC and ARC. What DKIM Still Can’t Prove DKIM today can prove that a domain signed some version of a message, but it still cannot establish […]
Categories: Deliverability, General
The first big SNDS update in years: What Changed and Why It Matters
2026/07/27 by Olivier Moulene.
Microsoft has made major changes to Smart Network Data Services (SNDS), its long-standing tool for monitoring IP reputation and complaint data for Outlook.com. The update brings a new portal, a modern OAuth 2.0 API, changes to complaint reporting, and reduced spam-trap visibility. Some changes are welcome improvements; others require deliverability teams to update existing monitoring […]
Categories: Deliverability, General
How Postmastery helped Lettermint scale European Email Infrastructure
2026/06/15 by Willem Stam.
As Lettermint grew from a small transactional email platform into a broader European email service provider, operational visibility and deliverability management became increasingly important. To support its growth, Lettermint selected KumoMTA for email delivery and Postmastery Console for analytics, monitoring, and reputation management. The combination enabled the team to automate bounce handling, reduce manual log […]
Categories: Case Studies, General, KumoMTA
Beyond 4xx & 5xx: The Truth About Email Bounces
2026/05/18 by Syed Alam.
At Postmastery, bounce analysis is part of our daily work. We process and analyse millions of bounce responses, and one pattern keeps coming back: many senders still rely on overly simple or inaccurate bounce classifications. The idea that “4xx means soft bounce” and “5xx means hard bounce” is easy to understand, but it does not […]
Categories: General
CNIL Recommendation on Email Tracking Pixels: What Changes and the Open Questions
2026/04/28 by Yves-Marie Le Pors-Chauvel.
A NOTE FOR INTERNATIONAL READERS The recommendation discussed in this article is a French regulatory initiative, issued by the CNIL, France’s data protection authority. At first glance, it may seem like a local compliance matter. It is not. Any sender, regardless of where they are established, who sends emails to recipients residing in France is […]
Categories: Deliverability, General
Postmastery on BFM Business (French TV) – Understanding Email Deliverability and Its Impact
2025/11/10 by Yves-Marie Le Pors-Chauvel.
We are proud to share that Postmastery was recently featured on BFM Business, in an interview hosted by Gilane Barret and produced in collaboration with OpenMedias. The goal of this interview was simple: explain who Postmastery is and make the often misunderstood topic of email deliverability accessible to everyone. Why talk about deliverability? Deliverability is […]
Postmastery to Attend M3AAWG 64 in Vancouver
2025/05/30 by Willem Stam.
Postmastery is excited to announce our participation in the upcoming M3AAWG 64th General Meeting, taking place from June 2–5, 2025, at the Hyatt Regency in Vancouver, Canada. This premier event brings together global experts in messaging, malware, and mobile security to collaborate on combating online abuse. The conference will feature a range of insightful sessions, […]
Categories: General