When a customer triggers a blacklisting on Marketo's shared IP range that customer is moved to a set of IPs we call the quarantined IP range. We do this to protect the health of our shared network and ensure the best deliverability possible for all of our customers on that network.
If you have received a Blacklist Notification from Marketo reporting that you have triggered a blacklisting your Marketo account is now in the quarantined IP range.
While you are in the quarantined range it is possible that you may experience a slight decrease in your deliverability rates. The reason for this is that you are now sending from a range made up of senders that have also caused other blacklist issues. All customers have received a notice of the listing and are in the process of repairing their database.
There are two ways to be removed from the quarantined IP range:
To ensure your best deliverability rates blacklist issues should be addressed right away to prevent further damage to your sending reputation. Furthermore, if no action is taken to improve list hygiene the issue will likely recur. Marketo's Privacy Team strongly recommend following the Blacklist Remediation steps.