Peter Schmidt
This post is part of the Email Security Foundations series. The mistakes that break SPF quietly SPF usually does not fail in loud or obvious ways. Mail does not bounce with a helpful error message. It just gets filtered, delayed, or rejected somewhere else. You only find out when someone eventually asks, “Did you get … Read more
If you run an on-premises Exchange Server or any Windows-based SMTP relay that sends mail to or receives mail from Exchange Online, then you might have a hard deadline coming up: March 22, 2026. Miss it, and you can risk breaking your mail flow, if the Root Certificates used by Exchange is not updated. What … Read more
This post is part of the Email Security Foundations series. What SPF actually does SPF, Sender Policy Framework, is simply a way to publish a list in DNS of which servers are allowed to send email for your domain. When a receiving mail server gets a message claiming to be from yourdomain.com, it looks up … Read more
This post is part of the Email Security Foundations series. The goal of the series is simple. Explain SPF, DKIM, DMARC, DANE, MTA‑STS, and BIMI in a way that actually helps Microsoft 365 admins run safer email. Before we go deep, here is the map In post #01 we looked at why email authentication still … Read more
We’re gearing up for another great morning with the Workplace Ninja User Group Denmark, and this time we’re diving deep into some of the most requested topics across Windows, Security and the Modern Workplace. Whether you’re hands-on in endpoint management every day or just curious about what’s new in the Microsoft 365 ecosystem, this meetup … Read more