On June 10th, some customers experienced email delivery issues after Intercom was flagged by a spam monitoring organization called Spamhaus. On June 25th, Intercom was fully removed from Spamhaus’s blacklist and normal email deliverability resumed.
We want to share what caused Intercom’s platform to be added to Spamhaus’s blacklist, what we did to restore service, and what we’re doing to prevent similar issues from happening in the future.
On May 25th, we experienced a spike in email volume across our customer base in what we believe to be GDPR-related outreach to their users. While these communications were well-intentioned, a group of our customers sent email to invalid email addresses or spam traps. Organizations like Spamhaus flag when emails are being sent to invalid addresses. Sending emails to invalid addresses is how companies can be placed on an email blacklist. In addition, a number of fraudulent spammers started using Intercom after our internal spam detection system encountered issues from an unrelated software upgrade, which again resulted in an increase of emails being sent to spam traps.
The combination of these events led Intercom to be fully blacklisted by Spamhaus.
Once we identified the root causes of the blacklisting, we immediately took the following actions:
1) Detected and removed the fraudulent spammers who signed up for Intercom
2) Temporarily restricted email sending for a small number of customers who were sending a high volume of emails being marked as spam
3) Helped customers who were inadvertently sending emails to spam traps improve their sending practices
As a result of these and other actions, we successfully reduced the the levels of spam and spam trap hits coming from our network. On June 21, Spamhaus started to remove us from their blacklist and our email deliverability began to return to normal.
We are now fully removed from Spamhaus’s blacklist.
We know this incident disrupted our customers’ businesses and are committed to putting better measures in place to lower the risk of high impact spam blacklist issues and the effect that they have on our customers. Here’s how we’re improving our spam detection systems:
Put better safeguards in place to prevent spammers from signing up for Intercom Implement monitors, metrics and incident alarms to track email patterns that could lead to a blacklisting event
We are also improving and updating our incident management process to allow for faster high impact resolution, management and communication if Intercom is affected by spam blacklists in the future. In addition, our customer support and sales teams will have better logs to help them pinpoint which customers are affected by spam or blacklist events. This will help us reach out to customers faster if an incident like this occurs in the future.
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 email@example.com or via the Messenger.