Basic concepts and target areas of email header analysis tools
The basis of communication in email infrastructure is a set of headers constructed based on the Internet message format defined by RFC5322 and the MIME standard defined by RFC2045.
This tool follows the specifications of these standardized protocols and automates the parsing of various header fields that detail the email delivery process and authentication information.
In particular, analysis of the Received field, which records changes in the communication path, the Authentication-Results field, which stores the authentication results judged by each relay server, the Received-SPF field, the DKIM-Signature field, and the ARC-Authentication-Results field, which ensures continuity of authentication even during transfer, is extremely important in evaluating the reliability of emails.
In addition, by accurately parsing the string patterns of the Return-Path field, which is the destination for bounce processing, and the Message-ID field, which guarantees uniqueness on a worldwide network, and converting each component into a logical data structure, it is possible to comprehensively understand complex header information that is difficult to visually inspect.
Transmission route hop time lag delay millisecond calculation and source IP address extraction model
Email passes through multiple email transfer agents before reaching the recipient. The Received header added at each relay point records a timestamp along with source and destination server information.
This system implements a time lag calculation algorithm that calculates communication delays with high precision in milliseconds by reconstructing the order of each hop that a message passes from reverse to forward and calculating the difference in timestamps between adjacent hops.
This allows you to quantitatively identify which network segment or relay server is experiencing processing congestion. Furthermore, we employ a model that uses regular expressions and lexical analysis to accurately extract source IP addresses in IPv4 and IPv6 formats from the complex string of Received headers.
This extraction process distinguishes from spoofed host names and local network bandwidth, identifies the real globally reachable source network, and provides accurate node information for subsequent analysis phases.
SPF, DKIM, DMARC authentication result determination logic
Sending domain authentication technology to prevent email sender spoofing is an essential security foundation in modern times. This tool is equipped with logic that reads the verification results of these three main authentication mechanisms from the header and makes a comprehensive judgment.
First, extract the judgment status such as Pass, Fail, SoftFail from the Authentication-Results or Received-SPF header regarding SPF authentication, which indicates whether the source IP address is allowed on the domain's name server.
Next, for DKIM, which ensures message integrity through cryptographic proof, we will analyze the signature algorithm, public key selector, and domain information in the DKIM-Signature field to check whether signature verification on the relay server was successful.
Furthermore, by integrating these SPF and DKIM results, for DMARC, which reflects the final domain owner's policy, we strictly determine whether the control policy of p equals reject, quarantine, or none is applied based on the specification in the header, and whether the alignment conforms to that policy.
By collating the multi-layered authentication results, we can reliably determine the authenticity of the email.
. Complete Browser Local Memory Processing of Loading EML Files and Header Texts
When handling email headers and EML files that contain highly confidential communication records, sending the information to an external server carries a serious risk of information leakage.
Therefore, this tool employs an architecture that completely completes the entire process from data loading to syntax analysis to final result output within the local memory space of the user's browser.
The EML file is expanded into memory using various JavaScript interfaces, and the header text is parsed using only client-side computational resources without any communication to the external network.
This completely in-memory processing, which is similar to an offline environment, structurally eliminates the possibility that sensitive information such as communication logs, internal network IP addresses, and individual employee email addresses will fall into the hands of third parties, providing a secure analysis environment that fully meets the strict compliance requirements and privacy protection policies of enterprise environments.
Transmission route interactive timeline display function
To adapt header information, which is often presented as a string of characters, to intuitive human cognitive models, the system has the ability to render parsed transmission route data as a visual, interactive timeline.
Each relay hop is placed as a node on the timeline, with the extracted IP address, hostname, and delay time from the previous hop graphically represented along the edge.
When a user hovers over or selects a particular node, details such as the original text of the unique Received header provided by that relay server and the SPF and DKIM authentication status at that hop are expanded on demand.
This interactive display approach makes it possible for even users without deep network knowledge to quickly and intuitively identify bottlenecks that are causing abnormal delays, or locations where suspicious third-party relay servers are intervening, even among dozens of lines of complex route information.
Spam email and spoofing phishing analysis and email delay investigation guide
Make the most of extracted and visualized header information to provide practical analysis techniques to combat cyber threats and operational obstacles.
If you suspect spoofing or a phishing attack, first check for a discrepancy between the domains in the Return-Path and From fields, then verify whether DMARC authentication has failed, and whether there is clever spoofing of the sender by exploiting the SPF record mechanism.
In addition, by unraveling ARC-Authentication-Results, we can trace how authentication was passed through legitimate transmission channels such as mailing lists, and identify the cause of quarantine of legitimate emails due to false positives.
On the other hand, when investigating email delivery delays that are disrupting business operations, we examine the millisecond delay time calculated on the timeline for each hop to determine whether the delay is due to a specific provider's spam filter processing or a queuing delay due to an overloaded internal transfer server.
These multifaceted analytical approaches provide a strong technical basis for maintaining email system reliability and quickly resolving security incidents.