Emails end up in the customer’s spam folder or get rejected, but why? DKIM is configured, SPF is set up, and DMARC is running. Everything was green in the last check, six months ago. After all, DKIM is supposed to ensure that emails are cryptographically signed and that neither the sender nor the content can be tampered with. This scenario is not an isolated case, but rather the result of treating DKIM as a one-time task rather than an ongoing one. In this blog post, you’ll learn what’s important when using DKIM and what common mistakes you should avoid when setting up and maintaining DKIM.
In many companies, email quarantine is considered a standard component of IT security. What may seem like a sensible protective measure at first glance actually entails significant legal risks in practice. A ruling by the Federal Court of Justice makes it clear that companies should reassess the consequences of email quarantine.
Your customers are under attack every day: with spoofed sender domains, authentic-looking phishing attempts, malicious attachments and AI-generated text that even experienced employees can no longer distinguish from genuine corporate communications. Email is and remains the preferred entry point for cybercriminals. The question isn’t whether your customer will be affected, but when. You are responsible for the security and satisfaction of your customers and for the quality of your recommendations. That is exactly why it’s worth taking a closer look at NoSpamProxy.
Imagine this: You receive an email with a seemingly harmless ZIP file attached, just a few kilobytes in size. Your system begins to unzip the file, and crashes. What follows is a system failure, wasted storage space, or, in the worst case, a gateway for further malicious code. The cause is a ZIP bomb, detonating within your IT infrastructure. In this blog post, we explain what ZIP bombs are, how they overload systems through extreme data compression and serve as a distraction for attacks, what variants exist, and how to effectively protect against them using multi-layered security mechanisms like NoSpamProxy.
CEO fraud, phishing, ransomware via infected attachments: Email remains the preferred entry point for attackers. In enterprise environments, the risk is magnified: more mailboxes, more locations, more entry points. And the attacks are becoming more sophisticated. AI-generated text, spoofed sender domains, context-specific attempts at deception – what used to be recognizable by poor spelling is now almost indistinguishable from a genuine sender. Enterprise organizations with hundreds or thousands of mailboxes, complex IT landscapes, and strict compliance requirements have unique needs. This is where NoSpamProxy comes in.
An accountant opens her mailbox in the morning. There is an email from her long-standing IT service provider – with an invoice for €14,800 attached. The IBAN looks strange, but a short note in the document explains: “Please note our new bank details.” She transfers the amount. Three weeks later, the real supplier sends the first reminder for the invoice – because the money was transferred to the wrong account. To an account abroad. The money is gone, irretrievably. Scenarios like this play out every day in companies around the world. This type of attack has a name: invoice fraud, a sub-form of what is known as Business Email Compromise (BEC). What is often overlooked is that there are always two victims. The recipient who transfers the money and the company whose identity was misused for the attack – and which may not even notice.
Traditional email security solutions check URLs when a message is received. If the linked page appears normal, the email is allowed to reach the inbox. But what if security systems see something different than the users who later click on the link? Cloaking techniques make this possible—and thus call into question a fundamental principle of URL filtering.
An accidentally deleted SPF entry, an unsuspecting email administrator, and weeks of undetected delivery problems—what sounds like a worst-case scenario actually happened. The case shows how 25Reports not only makes problems visible, but also enables them to be quickly resolved.
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Getting DKIM Right: The Key to Secure Email Communication18.05.2026 - 10:00
The Underestimated Risks of Spam and Quarantine Folders05.05.2026 - 10:00








