Exclaimer incident

Some messages are marked Undeliverable 'blocked using Spamhaus'

Notice Resolved View vendor source →

Exclaimer experienced a notice incident on December 5, 2025 affecting US: Server-Side: Mail Routing - Office 365, lasting 4d 18h. The incident has been resolved; the full update timeline is below.

Started
Dec 05, 2025, 02:55 PM UTC
Resolved
Dec 10, 2025, 09:53 AM UTC
Duration
4d 18h
Detected by Pingoru
Dec 05, 2025, 02:55 PM UTC

Affected components

US: Server-Side: Mail Routing - Office 365

Update timeline

  1. investigating Dec 05, 2025, 02:55 PM UTC

    Exclaimer Engineers are aware of an ongoing issue where one of our Server IPs looks to have been added to the Spamhaus eXploits Blocklist on multiple occasions. We have consistently noted that we are removed from the list automatically. However, we have implemented preventive action to reduce the impact on customers.

  2. monitoring Dec 08, 2025, 03:17 PM UTC

    We have now re-enabled email flow to return to all server IPs and have not noted any further blocks against the IP address at this time. Our Engineers are continuing to monitor the service with increased vigilance and have reached out to Spamhaus to investigate the cause of the intermittent blocks further. If you're experiencing issues when sending messages, please don't hesitate to reach out, and a member of our team will be able to investigate further.

  3. resolved Dec 10, 2025, 09:53 AM UTC

    No further instances of Exclaimer IPs being added to the Spamhaus eXploits Blocklist have occurred over the past 48 hours. If you're experiencing issues when sending messages, please don't hesitate to reach out to our support team, who can investigate further. https://support.exclaimer.com/hc/en-gb