On 6/28, Friday morning, part of Marketo's infrastructure was briefly listed with Spamhaus. Spamhaus provides a blacklist that email networks can use to help judge the reputation of an email. Email providers can use a listing with a blacklist like Spamhaus to help determine whether they should block mail delivery.
The listing was triggered by a customer mailing to a high volume of Spamhaus spamtrap email addresses. According to Spamhaus "spamtraps are email addresses which do not belong to real users. A spamtrap either never belonged to a real user, or did but was closed and rejected email for a significant period before being repurposed."
A listing like this is rare and Marketo reacted swiftly, resolving the listing within couple of hours. We continue to work very closely with the customer who triggered the listing to ensure this does not happen again. Even though they are rare, listings like this can occasionally occur in a high volume email sending environment and Marketo has alerting and monitoring set up for blacklistings and email blocking. Marketo maintains a good working relationship with Spamhaus and other blacklist providers to quickly resolve issues if they occur and we work with customers to maintain email best practices to avoid delivery impacting events.
Some customers who were sending from the impacted infrastructure may have seen some mail delivery delayed or not delivered because of the brief listing. If Marketo received a bounce indicating a delivery problem in most cases our servers would have retried delivering the mail for up to 24 hours. By retrying to deliver the mail at a later time, when the listing had time to be addressed, most impacted email was delivered instead of failing out right. The email addresses that did bounce when the listing was active are still mailable for future email campaigns. They bounces with a Spam Block Hard Bounce which does not set the Email=Invalid flag.
If you are interested in identifying the impacted leads in your database you can create a Smart List for email campaign sent Friday, 6/28.
SMART LIST
Filter: Email Bounced
(set constraints as needed, by time range or by email)
Constraint: Category is 1
This constraint identifies emails that bounces with a Spam Block Hard Bounce.
Once the leads are pulled you can add them to a new email campaign if you'd like to retarget them. [Leads Tab > Lead Actions > Flow Actions]
This did not impact all Marketo customers, only a portion of Marketo's infrastructure was briefly impacted. I apologize if you were impacted by this event.
Kiersti Esparza
.png)