Introduction

The SPFBL service is a combination of the concepts of SPF and DNSBL. The purpose of this service is to improve SPF processing and reduce the amount of external queries from an e-mail server, which uses SPF and at least some DNSBL service.

Once the service is started, queries can be made by client programs, such as the “spfbl.sh” script. Attention! The “spfbl.sh” script requires the “netcat” (command “nc”) package installed to work correctly.

The listing is made through the SPFBL ticket, which is sent together with the query’s SPF qualifier:

This ticket must be included in the “Received-SPFBL” header of the message for a possible future SPAM report.

If the service is configured to work with HTTP, tickets will be sent with their respective prefixes to the URL of the server who generated the ticket:

This last method facilitates the development of new tools, such as mail client plugins for example, so that reports are made directly by the recipient, wherever he is.

If the message is considered SPAM by the user, the message must be processed by the command “spfbl.sh spam”, which will extract the ticket contained in the “Received-SPFBL” field and send it to the SPFBL service:

Each report expires seven days after the date of receipt of the message and can only be reported up to five days after receipt.

Official project link: https://github.com/leonamp/SPFBL