The Unpredictability of Blacklists

The first signals of blacklisting
Blacklists are maintained by a wide range of independent organizations, internet providers, and system administrators each with their own policies, thresholds, and update intervals. This makes blacklisting a highly unpredictable and inconsistent process.

A sender may be blacklisted without notice, and in many cases, there is no clear explanation or formal appeals process. Even clean senders can be affected due to shared IP ranges, outdated reputation data, or overly aggressive filtering rules. What’s accepted by one server may be rejected by another, even for identical content.

So, keep in mind, for this reason, email delivery is never fully guaranteed,

A common example is Microsoft’s free email services, such as Outlook.com or Hotmail.com, which often reject messages with a S3150 blacklist response. Unfortunately, when attempting to contact their system administrators, blacklist status is frequently denied, even when a live bounce message clearly confirms the rejection from their servers.

Anti-Spam Measures and Blacklisting Policy
As part of our ongoing efforts to combat spam, Concera actively uses blacklists to identify and block IP addresses associated with spam-sending systems. We currently enforce a strict anti-spam policy. In addition to blacklisting, such IP addresses are also denied access to our systems through the use of a dynamic firewall.

Protecting Your Hosting and Email Services
We aim to provide our hosting customers with the highest possible service quality. That includes not only system security, but also effective email handling with minimal disruption from spam. This is a complex and resource-intensive process involving, not limited to:

• Advanced spam filters
• Internal and external blacklists
• A dynamic firewall to respond in real-time

Whenever an IP address is flagged as suspicious, it is immediately added to our blacklist and blocked by our firewall. Some addresses are automatically released after a specific period, while others require manual review and removal.

Check your and our blacklist status with the links below:
Click here to check if you're own ip address (216.73.216.234) is blacklisted.
Click here to check if Concera is blacklisted.

If your IP address is listed on our blacklist, please contact us to request removal and/or to have it added to our whitelist. Adding your IP address to the whitelist ensures that it is marked as trusted and can no longer be automatically blacklisted by our system. By using Concera’s email services, you expressly acknowledge and agree that Concera shall not, under any circumstances, be held liable for any consequences arising from blacklisting, whether caused by Concera or by third parties, that may result in: partial or full disruption of Concera’s services or email delivery failure, emails being received by clients of Concera or emails being marked or treated as spam by Concera or bij the receiver. Keep in mind that email delivery or receiving is never guaranteed