How to use the command 'spfquery' (with examples)

The spfquery command is a powerful tool used in email validation processes to query Sender Policy Framework (SPF) records. SPF records specify which mail servers are allowed to send email on behalf of a domain, and spfquery helps validate whether an email sender’s IP address is authorized according to these records. This is crucial for maintaining email security by preventing spoofing and ensuring that legitimate emails are not improperly filtered.

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:

Email spoofing, where malicious actors send emails pretending to be from a legitimate sender, is a common issue. Checking SPF records is an essential part of defending against such attacks. By using spfquery with an IP address and a sender’s email, you can verify whether the given IP address is authorized to send emails on behalf of the specified sender’s domain. This can help email administrators troubleshoot delivery issues and prevent fraudulent emails from reaching their recipients.

Explanation:

• -ip 8.8.8.8: This argument specifies the IP address that you want to check against the SPF record of the domain. In this example, we’re querying whether the IP address 8.8.8.8 is permitted to send emails for the domain of the sender email provided.
• -sender sender@example.com: This argument is specifying the email address that is believed to be sending the email. The domain part of this email (example.com) is used to look up its SPF record.

Example Output:

pass

In this output, “pass” indicates that the IP address is permitted according to the SPF record of the sender’s domain, meaning it is recognized as a legitimate sender.

Use case 2: Turn on debugging output

Code:

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

Motivation:

Debugging output is exceedingly valuable during troubleshooting and complex evaluations of SPF records. When issues arise regarding email delivery or suspected unauthorized usage of sending domains, increased verbosity via debugging helps in diagnosing the underlying problems. This allows administrators to observe how the spfquery command processes the SPF lookup and what factors might be affecting the outcome.

Explanation:

• -ip 8.8.8.8: Similar to Use Case 1, this specifies the IP address being checked against the SPF record of the sender’s domain.
• -sender sender@example.com: This defines the email address in question. The domain is extracted from this address to perform the SPF lookup.
• --debug: This option is pivotal for troubleshooting as it enables detailed output explaining every step and decision made by the spfquery process.

Example Output:

Evaluating SPF record: v=spf1 ip4:8.8.8.8 -all
IP '8.8.8.8' matches 'ip4:8.8.8.8'
SPF result: pass

The debug output includes the specific portion of the SPF record being evaluated and how it relates to the IP address, providing detailed insights into why a particular result was returned.

Conclusion:

The spfquery command is a vital tool for anyone involved in managing email security and delivery by allowing deep insights and validation of SPF records. With use cases ranging from basic validation to in-depth debugging, it can help ensure email systems are both secure from spoofing and capable of delivering legitimate communications effectively.