Summary
Identifying the source and purpose of emails originating from unrecognized IP addresses involves a multi-faceted approach. Core techniques revolve around email header analysis, using tools to parse 'Received:' fields to trace the email's path. Services like SenderScore and Senderbase aid in identifying associated domains. Reverse DNS lookups and IP ownership research (using command-line tools or Google) can further pinpoint the source. Analyzing DMARC reports helps identify IPs failing authentication, while internal investigations can reveal the use of Oracle's services. Checking blacklists provides insights into the IP's reputation. Identifying IP ranges assists in pinpointing the originating email marketing service. Email tracking reveals delivery, opens, and location data. Preventing spoofing is best achieved by setting up DKIM, SPF, and DMARC. Understanding email header structures and authentication protocols is crucial.
Key findings
- Email Header Analysis: 'Received:' headers and header analyzer tools are critical for tracing the path and source of emails.
- IP Reputation Services: SenderScore and Senderbase help identify domains associated with an IP address.
- IP Ownership Lookup: Command-line tools and Google can reveal the owner of the IP address.
- DMARC Reports: DMARC reports highlight IPs failing authentication checks, indicating potential issues.
- Blacklist Checks: Checking blacklists helps determine if the IP is associated with spam or malicious activity.
- Authentication Protocols: DKIM, SPF, and DMARC are crucial for preventing spoofing and verifying email sources.
- Email Tracking: Email tracking provides valuable data on delivery, opens, and user location.
Key considerations
- Technical Proficiency: Effective email header analysis requires technical expertise and familiarity with various tools.
- rDNS Limitations: Reverse DNS records might not always be accurate or provide useful information.
- Holistic Approach: Combining various methods—header analysis, IP lookups, and blacklist checks—offers the most comprehensive understanding.
- Spoofing Prevention: Implementing and maintaining DKIM, SPF, and DMARC records is essential for preventing email spoofing.
What email marketers say
6 marketer opinions
Identifying the source and purpose of emails from unrecognized IP addresses involves analyzing email headers, checking the 'Return-Path', using IP lookup tools, and employing header analyzer tools. Implementing email authentication protocols like DKIM, SPF, and DMARC is crucial for preventing spoofing and tracing legitimate sources. Email tracking techniques can provide information about delivery, opens, and geographical locations.
Key opinions
- Header Analysis: Email headers contain vital routing information; tools can decode them.
- Return-Path Check: The 'Return-Path' header reveals the actual sender, bypassing spoofed 'From' addresses.
- IP Lookup: IP lookup tools identify the origin of the sending server.
- Header Analyzers: Specialized tools parse headers, simplifying the process of identifying source IPs.
- Email Tracking: Email tracking provides information on opens, location, and client.
Key considerations
- DKIM/SPF/DMARC: Implementing DKIM, SPF, and DMARC prevents spoofing and assists in tracing emails.
- Email Spoofing: Always be wary of potential email spoofing.
- Tool Usage: Familiarize yourself with email header analysis tools for effective investigation.
Marketer view
Email marketer from Stack Overflow explains that examining the full email header is crucial, looking for 'Received:' fields to trace the path and identify originating servers. They advise using online tools to parse and analyze these headers.
19 Jul 2021 - Stack Overflow
Marketer view
Email marketer from WhatIs.com shares the definition of Email Tracking. This is the technique of monitoring delivery of email messages in order to learn if a message was delivered, opened, and read; what email client was used; and, sometimes, from what geographical location.
19 Sep 2023 - WhatIs.com
What the experts say
7 expert opinions
Identifying the source and purpose of emails from unrecognized IP addresses can be achieved through various methods. These include using SenderScore, Senderbase, and reverse DNS (rDNS) lookups via Google. Command-line tools and Google searches can help find the IP address owner. DMARC reports, internal inquiries, and tech team consultations regarding DKIM selectors and key requisition information are useful. Querying blacklists and analyzing IP address ranges to identify email marketing services can also provide insights. Keep in mind not all IPs have helpful rDNS records.
Key opinions
- Sender Reputation Services: Tools like SenderScore and Senderbase provide domain listings associated with an IP.
- rDNS Lookups: Reverse DNS lookups can reveal the hostname, providing clues about the IP's purpose (although not always reliable).
- IP Ownership Research: Command-line tools and Google can identify the owner of the IP address.
- DMARC Reporting: DMARC reports can reveal sending IPs failing authentication checks.
- Internal Investigation: Inquiring internally and consulting tech teams about DKIM records can uncover the source.
- Blacklist Checks: Checking if the IP is on any blacklists can indicate if it's associated with spam or malicious activity.
- IP Range Analysis: Identifying the IP range and associated email marketing service can reveal its intended use.
Key considerations
- rDNS Reliability: Reverse DNS records might not always be accurate or helpful.
- Internal Resources: Investigating internally and consulting with the tech team may require significant effort.
- Context is Key: Gathering information from multiple sources provides a more complete understanding.
Expert view
Expert from Spam Resource explains the method of querying various blacklists to see if an IP address is listed. If it is, the listing notes will usually provide some insight as to the reasons it was blacklisted.
30 Nov 2024 - Spam Resource
Expert view
Expert from Word to the Wise shares the method of using IP address ranges to attempt to identify an email marketing service and then use tools to query their use policy.
6 Jun 2021 - Word to the Wise
What the documentation says
6 technical articles
Identifying the source and purpose of emails from unrecognized IP addresses relies heavily on email header analysis and understanding authentication protocols. Examining 'Received:' headers, as detailed by Google Workspace Admin Help and Microsoft Support, can trace the email's path and reveal potential spoofing. RFC Editor provides technical specifications for interpreting these headers. DKIM.org explains how to identify the signing domain using the 'd=' tag in the DKIM-Signature header. IETF outlines SPF's role in preventing sender address forgery. DMARC.org details how DMARC builds upon SPF and DKIM to enhance email channel protection through reporting and authentication analysis.
Key findings
- Received: Headers: 'Received:' headers trace the email's path and identify potential spoofing or forwarding.
- Header Structure (RFC): RFC specifications provide a framework for understanding and interpreting email headers.
- DKIM Signing Domain: The 'd=' tag in the DKIM-Signature header reveals the signing domain.
- SPF Prevents Forgery: SPF verifies that sending mail servers are authorized by the domain.
- DMARC Enhances Protection: DMARC builds on SPF and DKIM, adding reporting and authentication analysis.
Key considerations
- Technical Expertise: Effective header analysis requires technical knowledge and experience.
- Comprehensive Approach: Combining header analysis with SPF, DKIM, and DMARC checks offers the best protection.
- Organizational Insight: Understanding internal email flow, as highlighted by Microsoft Support, is critical.
Technical article
Documentation from DKIM.org details how to identify the signing domain. Checking for the d= tag within the DKIM-Signature header field will display the domain that signed the message.
11 Jul 2022 - DKIM.org
Technical article
Documentation from IETF details the purpose of SPF, which is to prevent sender address forgery. The goal of SPF is to enable recipient mail systems to verify that a message purporting to originate from a specific domain was authorized by the domain's administrative management.
5 Aug 2023 - IETF
Does x-originating-ip impact email deliverability?
What are common terms for the envelope.from domain in email marketing?
What could cause unfamiliar IP addresses to appear in PMT, and what steps should be taken to investigate?
How can you identify the source of unsolicited emails and prevent data leaks?
Besides Spamhaus, what blocklists are important for email marketers to monitor?
How can I identify the ESP used to send a spam email using the email headers?
How can I check if an email is sent from a dedicated or shared IP without contacting the ESP?
How do I perform a reverse DNS lookup and interpret the results?
Can I use DMARC with shared IP addresses?
