Message Deliverability: IP Blacklisting Event
Incident Report for Intercom
What happened:

We recently experienced a spike in email volume across our customer base in what we believe to be GDPR-related outreach to users. While these communications were well-intentioned, a group of our customers sent email to inactive users, including spam trap addresses.

This led a spam monitoring organization called Spamhaus to flag Intercom in their blacklist. As a result, over the past two weeks, approximately 16% of our outbound emails were not delivered (14% to Microsoft domains, 1% to Apple domains, and the remainder to other domains). Emails going to any Google Apps, Gmail, Yahoo and AOL addresses were delivered as expected.

What we did about it:

Complete resolution of this issue has been the highest priority for our engineering teams for the last 2 weeks. We worked quickly to remove ourselves from the Spamhaus list and bolster our capabilities to detect irregularities and ensure email deliverability.

All of our sending IPs have now been delisted by Spamhaus as a result of extensive work on improving the quality of emails sent via Intercom. All emails to users and admins should be delivering as normal. In order to achieve this we've had to put more aggressive measures in place to ensure our customers are following best practices. We do not intend to keep these long term. This may have an effect on who you are able to email from Intercom at the moment. Please reach out if you are having issues.

To prevent incidents like this happening again, we’re investing heavily in spam monitoring technology and detection resources, so we can identify irregular behaviour before it becomes an issue. This way we can help our customers maintain their reach and stay in good standing.

We are going to significantly increase the amount of engineering capacity dedicated to email deliverability, including more comprehensive checks and balances to ensure proper use of Intercom.

We appreciate that you entrust us to help you communicate with your customers and it’s not something we take lightly. These actions and others we’re taking should prevent similar incidents from happening again. If you have specific questions, do not hesitate to contact our Support team at or via the Messenger.
Posted 26 days ago. Jun 25, 2018 - 17:16 UTC
This incident affected: Intercom message delivery (Small message delivery, Medium message delivery, Large message delivery, Admin notifications).