How Spam Filters Sneakily Caused Us to Lose Business

TL;DR:

• Spam filter blocked our client emails
• Email vendor refused to give us control over spam filtering
• Email vendor expected our client to solve the issue themselves adding more friction to the relationship
• WTF Spam filters?

Introduction

Imagine this: your business depends on email for critical client interactions, transactional updates, and everyday operations. Now, picture this lifeline suddenly severed—not because of something you did, but because an invisible gatekeeper decided your emails don’t belong. Sounds far-fetched? It happened to us, and it could happen to you too.

Today, we’re sharing our story of how spam filters—those silent gatekeepers of email—disrupted our business, risking client relationships and forcing expensive, time-consuming fixes. This isn’t just our story; it’s a wake-up call for anyone relying on email as a cornerstone of their operations. Here’s what happened, why it matters, and what needs to change.

Chaging Email Provicers: Because Webmail and Security

For years, we relied on HKN, a German email provider using Zimbra. Zimbra’s powerful features and reliability served us well, particularly its robust webmail interface. Webmail isn’t just a convenience for us—it’s a deliberate choice to enhance security. Downloading emails to a local email client, while common, introduces significant risks by effectively allowing anyone with your email address to send potentially harmful files to your computer.

This practice opens the door to vulnerabilities in email clients, where a single malicious attachment can compromise an entire system. By relying on webmail, we isolate emails and attachments in the cloud, reducing exposure to local infrastructure risks and ensuring that email remains secure. Or, at least, a bit more secure.

However, as our needs evolved, we wanted more from our email provider: a modern interface, seamless integration with cloud storage all while offering enhanced security features like DKIM enforcement and two-factor authentication (2FA). These requirements set the bar high, and GDPR compliance was non-negotiable. Surprisingly, many email providers—even within the EU—fall short of GDPR’s principles of Data Protection by Design and Default. The absence of 2FA, in particular, is a clear signal that a provider may not take data protection seriously.

After an extensive search, we found Infomaniak, a Swiss provider that appeared to check all our boxes. Their focus on privacy, modern interface, and compliance with GDPR made them seem like the ideal choice. Unfortunately, what began as a promising partnership quickly unraveled when we encountered a deeper issue: the opaque and unaccountable nature of spam filtering systems they implemented.

The Hidden Cost of Spam Filters

The problems began when our emails started disappearing into a black hole. A client using Microsoft 365—a globally trusted platform—was unable to reach us, with their messages blocked by Abusix, a third-party spam filter. Later, we discovered our own transactional emails sent via Brevo were also being blocked, flagged by SpamCop.

These were just the cases we knew about. The thought of how many emails might have been silently rejected without our knowledge was chilling.

Spam filters like these often operate as unaccountable gatekeepers, dictating which emails get delivered and which don’t, with little transparency or recourse. Businesses are left scrambling to fix issues that are often out of their control.

A Costly Workaround

To address the issue with transactional emails, we had to switch to a dedicated IP for transaction email delivery. This change was forced upon us by SpamCop, even though we had been delivering emails successfully to major providers like Gmail and Outlook for years without issues. The silver lining was that while Dedicated IP solution ain't cheap, at least Brevo makes it fairly straight forward to deploy.

Fixing the issue with client emails was even more challenging. Our client, understandably, wasn’t willing to navigate the convoluted process of disputing their emails being marked as spam. And Infomaniak’s response? They refused to give us control over spam filtering or whitelist the client, instead suggesting we ask the client to solve the issue themselves. This approach ignored the reality of customer relationships: every added hurdle risks driving clients away.

The Flaws in Spam Filtering

The crux of the problem lies in how spam filters are used. While they aim to protect users from malicious actors, their opaque algorithms often block legitimate senders. Worse, email providers outsource this critical functionality to third-party services like Abusix and SpamCop, relinquishing accountability for email delivery.

Modern email authentication protocols — SPF, DKIM, and DMARC - are well-established tools for verifying email authenticity. Yet, providers continue to rely on these opaque, middleman-driven systems. The result is a lack of transparency and control for users.

Compounding the issue is the failure to inform users when emails are rejected. Without notifications, businesses remain unaware of missed opportunities and frustrated clients. This opacity undermines trust in email as a reliable communication channel.

The Way Forward

So, what’s the solution here? It’s not complicated, but it does require email providers to rethink how they handle spam filtering. Here’s what we’d like to see happen:

First, let’s stop blindly trusting these third-party spam lists. Providers already have tools like SPF, DKIM, and DMARC to verify whether an email is legitimate or not. Why not make those the go-to solution instead of relying on opaque systems like Abusix and SpamCop? They’re outdated and often wrong, as we’ve painfully learned.

Second, transparency matters. If an email gets blocked, we need to know. A simple notification—“Hey, we rejected this email for XYZ reason”—would go a long way. It gives businesses the chance to step in, assess the situation, and avoid missing important messages. Keeping users in the dark helps no one.

And lastly, give us some control! We’re paying for email services; the least we should get is the ability to adjust spam settings. Let us decide if we want to take the risk of reviewing flagged emails or whitelisting specific senders. This one-size-fits-all approach doesn’t work for everyone, especially businesses where every missed email could mean a lost opportunity.

The bottom line? Email providers need to focus on making sure emails actually get delivered to the people they’re intended for. Blocking spam is important, sure, but not at the expense of breaking communication entirely.

And Finally

This experience hurt. We lost time, money, and confidence in a system we rely on daily. The worst part? It could happen to anyone. Email is essential for businesses, yet the tools meant to protect us—like spam filters—can become the very obstacles that undermine communication.

We learned a hard lesson: the Internet doesn’t have to be this way. Let’s stop accepting systems that make communication harder and demand better design, transparency, and accountability. It’s time to make the Internet work for us, not against us