The ‘spfquery’ command is used to query Sender Policy Framework (SPF) records in order to validate e-mail senders. SPF is an email validation system that allows domain owners to specify which mail servers are authorized to send email on behalf of their domain. The ‘spfquery’ command can be used to check if an IP address is allowed to send an email from a specified email address, and it also provides an option to turn on debugging output for additional information.

Use case 1: Check if an IP address is allowed to send an e-mail from the specified e-mail address

Code:

spfquery -ip 8.8.8.8 -sender sender@example.com

Motivation: This use case is useful when you want to verify whether an IP address is allowed to send an email from a specific email address. It helps to ensure that the email is coming from a legitimate source and not from a spam or malicious sender.

Explanation:

• spfquery: This is the command to be executed.
• -ip 8.8.8.8: This argument specifies the IP address that needs to be checked.
• -sender sender@example.com: This argument specifies the email address that is being verified.

Example Output:

Received-SPF: pass (example.com: domain of sender@example.com designates 8.8.8.8 as a valid sender) client-ip=8.8.8.8;

In the example output, the email sender’s domain (example.com) designates the IP address 8.8.8.8 as a valid sender, indicated by the “pass” status.

Use case 2: Turn on debugging output

Code:

spfquery -ip 8.8.8.8 -sender sender@example.com --debug

Motivation: Enabling debugging output can provide additional information about the SPF record validation process, helping with troubleshooting and understanding the result.

Explanation:

• spfquery: This is the command to be executed.
• -ip 8.8.8.8: This argument specifies the IP address that needs to be checked.
• -sender sender@example.com: This argument specifies the email address that is being verified.
• --debug: This flag enables debugging output, providing detailed information about the SPF record validation process.

Example Output:

SPF debug: example.com (raw SPF record) = v=spf1 mx a -all
SPF debug: example.com (parsed SPF record) = v=spf1 mx a -all
SPF debug: example.com (after macro expansion) = v=spf1 mx a -all
SPF debug: example.com (final policy) = v=spf1 mx a -all
Received-SPF: pass (example.com: domain of sender@example.com designates 8.8.8.8 as a valid sender) client-ip=8.8.8.8;

In the example output, the debugging output shows the raw SPF record, the parsed SPF record, the SPF record after macro expansion, and the final policy. The email sender’s domain (example.com) designates the IP address 8.8.8.8 as a valid sender, indicated by the “pass” status.

Conclusion:

The ‘spfquery’ command is a useful tool for validating e-mail senders by querying Sender Policy Framework (SPF) records. It allows you to check if an IP address is allowed to send an email from a specified email address and provides debugging output for troubleshooting purposes. By using this command, you can ensure that emails are sent from legitimate sources and prevent spam or malicious senders.