The Senderscore Reputation Network or Return Path Blocklist (RPBL) is made up of IP addresses that have exhibited spam-like behavior or content and are based on Return Path’s own data as well as that from their partnerships.
Listings are done on an IP level, and overall have a low impact on message delivery. The list is offered to anyone free of charge, and each provider chooses for themselves if/how they implement the list.
Reason for listing
IPs can be listed for:
- Sending messages containing suspicious attachments
- Email authentication failures or discrepancies (failing SPF and/or DKIM)
- Sending messages to spam traps
- Botnet sending behavior
Delisting can be requested by entering the IP address in the form on the RPBL website. After submitting the request, Return Path will share the reason for the listing with you so that you may address the issue if you have not done so already. Relisting can occur if the root problem has not been sufficiently addressed.
If you were listed for sending messages with suspicious attachments, review the attachments you have been sending, and if changes need to be made to either the content or the attachment type.
If you were listed for authentication failures, review your sending domains’ DNS records to ensure that the proper SPF and DKIM records are in place. Furthermore, review your traffic to ensure alignment between the Envelope From and Header From values.
If you were listed for sending to spam traps, list hygiene is key to make sure this does not reoccur. You may want to leverage a service like Mailgun's Email Verifications to help with this.
If you were listed for botnet behavior, you may either be operating a botnet, or your IP is being abused by a botnet operator. You will need to reach out to your infrastructure provider for further assistance.