93 How to Analyze Email Headers for Phishing and Stay Safe Online

In today's digital world, staying protected from online threats is more important than ever. One common way scammers try to trick us is through phishing emails, which look legitimate but aim to steal your personal information. While looking at the email itself is a good start, understanding how to analyze email headers for phishing can give you a much deeper insight into where an email truly originated and whether it's a genuine communication or a malicious attempt to deceive you.

Decoding the Email's DNA: Understanding the Header

Think of email headers as the return address and postage stamp on a physical letter, but much more detailed. They contain a lot of technical information about the journey an email took from sender to recipient. Learning how to analyze email headers for phishing is a crucial skill because it allows you to look beyond the sender's displayed name and email address, which can be easily faked. By examining these headers, you can uncover the true origin of the message, revealing inconsistencies that are red flags for phishing attempts.

The information within an email header is presented in a structured way, but it can seem overwhelming at first. Here's a breakdown of some key components you'll want to pay attention to when you're trying to figure out how to analyze email headers for phishing:

  • Received lines: These show the servers the email passed through. The order is important; the top 'Received' line typically indicates the last server that handled the email before it reached you, and tracing them downwards shows the path it took.
  • Return-Path: This specifies the address where bounced emails should be sent. It's often different from the 'From' address, which can be a giveaway.
  • Authentication-Results: This section tells you if the email passed checks like SPF, DKIM, and DMARC. These are security measures designed to verify the sender's identity.

The importance of thoroughly examining these header details cannot be overstated because they provide objective evidence of an email's path and authenticity, which the visible content often masks. Here’s a simple way to visualize the process:

Header Field What to Look For Phishing Red Flag
Received: IP addresses and server names. Unusual or unexpected IP addresses, servers from distant locations, or servers not associated with the purported sender.
Return-Path: The email address for bounces. A different domain or sender than the 'From' address.
Authentication-Results: Pass/Fail for SPF, DKIM, DMARC. Failing results indicate the email hasn't been properly verified.

How to analyze email headers for phishing: Checking the originating IP address

  1. Identify the 'Received:' lines.
  2. Look for the IP address associated with the earliest 'Received:' entry (often at the bottom).
  3. Use an IP lookup tool to find the geographical location and ISP associated with that IP.
  4. Compare this information with the purported sender's location and known legitimate servers.
  5. An IP address from a country or region far from the sender's usual location is suspicious.
  6. An IP address belonging to a known spamming network is a major red flag.
  7. The IP might point to a public Wi-Fi hotspot, which is uncommon for official business correspondence.
  8. A generic IP address from a large cloud provider might be used to mask the true origin.
  9. The IP could be associated with a newly registered domain, indicating a quickly set-up phishing operation.
  10. The IP might be part of a botnet, used to send mass phishing emails.
  11. If the email claims to be from a specific company, check if the IP belongs to that company's known infrastructure.
  12. A mismatch in IP address location and the domain's registered location is a warning sign.
  13. The IP might be dynamically assigned, meaning it changes frequently, which can be suspicious for a stable organization.
  14. An IP address that doesn't resolve to a clear hostname could be an attempt to obscure the sender.
  15. If you see multiple 'Received:' lines, trace them back to find the very first server that accepted the email.
  16. An IP address that redirects to a completely unrelated service suggests manipulation.
  17. The IP might be located in a country known for cybercrime.
  18. A simple check of the IP address against publicly available blacklists can reveal if it's been flagged for malicious activity.
  19. The presence of a VPN IP address can indicate an attempt to hide the true sender.
  20. If the IP is associated with a free webmail service, it's unlikely for a legitimate business communication.

How to analyze email headers for phishing: Verifying sender authentication

  1. Locate the 'Authentication-Results:' header.
  2. Check for SPF (Sender Policy Framework) results. A 'pass' is good, 'fail' is bad.
  3. Examine DKIM (DomainKeys Identified Mail) results. A 'pass' indicates the email's content hasn't been tampered with.
  4. Look for DMARC (Domain-based Message Authentication, Reporting & Conformance) results. This policy helps determine what to do with emails that fail SPF or DKIM.
  5. A 'fail' for SPF means the sending server wasn't authorized by the domain owner.
  6. A 'fail' for DKIM means the digital signature was invalid, suggesting the email might have been altered.
  7. If SPF and DKIM pass, but DMARC indicates a rejection policy, the email might still be blocked by your mail server.
  8. Be wary if 'Authentication-Results:' is missing entirely, as legitimate mail servers usually include this.
  9. If the email shows 'softfail' for SPF, it means the sender isn't explicitly authorized but not strictly forbidden, which can still be a sign of spoofing.
  10. A mismatch between the domain in the 'From:' address and the domain used for SPF/DKIM checks is a major indicator of phishing.
  11. Some phishing emails might have forged 'Authentication-Results:' headers, so this isn't foolproof but is a strong indicator.
  12. If the email is from a well-known company, and its authentication results are consistently failing, it's highly suspicious.
  13. You can manually check SPF and DKIM records for a domain using online tools if you're highly suspicious.
  14. A 'neutral' SPF result suggests the domain owner hasn't set up SPF records properly or hasn't specified whether the server is allowed to send mail.
  15. If an email claims to be from Google but fails Google's own authentication checks, it's definitely phishing.
  16. Pay attention to the specific details within the authentication results, such as the signing domain for DKIM.
  17. If the authentication checks are passed for a different domain than the one in the 'From' address, it's a spoof.
  18. The absence of DMARC policies can sometimes be exploited by phishers.
  19. Remember that even if authentication passes, the content of the email could still be malicious, but failed authentication is a very strong warning.
  20. A sender might intentionally use a sub-domain that isn't covered by the main domain's authentication, which can be a tactic.

How to analyze email headers for phishing: Examining the 'Received' path

  1. Start from the bottom 'Received:' line and work your way up.
  2. Each 'Received:' line represents a hop the email made through different servers.
  3. Look for inconsistencies in server names or IP addresses.
  4. Is the first server in the path a known, legitimate mail server for the purported sender's domain?
  5. Are there any unexpected jumps to servers in different countries or continents?
  6. Does the sequence of servers make logical sense for the purported sender?
  7. A rapid succession of 'Received:' lines from obscure or identical servers can be a sign of automated phishing.
  8. If the email claims to be from a bank, but the 'Received:' lines show it passed through servers in Russia, that's a huge red flag.
  9. Be aware that legitimate emails can sometimes take indirect routes due to mail system configurations.
  10. However, egregious deviations from normal paths are suspicious.
  11. Use IP lookup tools for each 'Received:' entry to understand the origin of each server.
  12. If the server names appear to be randomly generated or nonsensical, it's likely a fake.
  13. Some phishing emails will show a 'Received:' line from your own email provider first, making it look like it came from within.
  14. Trace the IP address of the sending server back to its registered owner.
  15. If the path seems unnecessarily long or convoluted, it could be an attempt to obscure the true source.
  16. Compare the time stamps on the 'Received:' lines; they should generally show a progression.
  17. Look for IP addresses that are known to be associated with spam or phishing campaigns.
  18. If the email originates from a service that the sender wouldn't normally use (e.g., a personal Gmail account for a corporate executive), it's suspicious.
  19. The actual source of the email might be hidden behind many proxies or compromised servers.
  20. A lack of clear server identification in the 'Received:' lines is problematic.

How to analyze email headers for phishing: The 'From' versus 'Reply-To' fields

  1. Check the 'From:' field carefully. This is what you see as the sender.
  2. Look for a 'Reply-To:' field. This is where replies will actually go.
  3. If the 'From:' address looks legitimate, but the 'Reply-To:' address is different and suspicious, it's a phishing attempt.
  4. For example, 'From: @realbank.com' but 'Reply-To: @fakedomain.net'.
  5. Sometimes, the 'Reply-To:' field is intentionally left blank. This means replies will go to the address in the 'From:' field.
  6. However, in phishing, the 'From:' address itself is often spoofed, so even if 'Reply-To' is blank, the sender isn't who they seem.
  7. The 'From:' field can be easily forged, making it a less reliable indicator on its own.
  8. The 'Reply-To:' field is more critical if it's present and different from the 'From:' field.
  9. If the 'Reply-To:' address is a personal email account for what should be a business communication, be very suspicious.
  10. A large discrepancy between the 'From:' domain and the 'Reply-To:' domain is a strong indicator.
  11. Scammers might use a familiar 'From:' name but a slightly different domain in the actual email address to trick you.
  12. Always examine the full email address, not just the display name.
  13. If you click 'reply' and the 'To:' address that pops up is not what you expected, it's a sign.
  14. The 'Sender:' header can also be present and is used when an email is sent on behalf of another person.
  15. If the 'Sender:' header is present and different from the 'From:' header, investigate further.
  16. A mismatch between the domain of the 'From:' address and the domain used in the SPF/DKIM checks in 'Authentication-Results' is also crucial.
  17. The 'Return-Path:' is another important field that indicates where bounce messages are sent.
  18. If the 'Return-Path:' is different from the 'From:' and 'Reply-To:' addresses, it warrants close inspection.
  19. Phishers often rely on the user not checking these hidden fields.
  20. The presence of both a 'From:' and 'Reply-To:' field is common, but the contents are what matter.

    21. How to analyze email headers for phishing: Identifying forged or missing information

    1. Be alert for missing 'Received:' lines, which can indicate manipulation.
    2. If key headers like 'Authentication-Results' or 'Return-Path' are absent, it's suspicious.
    3. Look for inconsistencies in timestamps across different 'Received:' lines.
    4. Scammers might intentionally remove or alter header information to hide their tracks.
    5. If the 'Message-ID' looks unusual or is missing, it could be a sign of a forged email.
    6. Check if the date and time in the header align with the purported sending time.
    7. An email claiming to be urgent, sent at 3 AM, might be less suspicious than one with header inconsistencies.
    8. Beware of emails where the sender's IP address is the same as yours or your company's network, if it's not supposed to be.
    9. If you see 'X-Headers' that are clearly not standard and seem to be custom-inserted, they might be used for deception.
    10. A missing 'Subject:' line is highly unusual for legitimate emails.
    11. If a crucial piece of information, like the domain name in the sender's address, is misspelled, it's a forgery.
    12. The 'MIME-Version:' and 'Content-Type:' headers are usually standard; if they are missing or look odd, investigate.
    13. Some advanced phishing may involve cleverly crafted headers that mimic legitimate ones.
    14. The absence of a DKIM signature when one is expected from the sender's domain is a red flag.
    15. If the email's apparent sender doesn't match the originating IP address or servers, it's forged.
    16. Be cautious if the header information seems overly simplistic or incomplete for the supposed sender.
    17. Some email clients might clean up headers, so what you see might not be the absolute raw original.
    18. If the sender claims to be from a large organization, look for evidence of their standard mail server infrastructure in the headers.
    19. The 'X-Mailer' header might indicate the software used to send the email; unusual entries can be suspicious.
    20. In short, any deviation from expected, standardized header information can be a clue.

    How to analyze email headers for phishing: Using external tools for analysis

    1. Copy the entire email header text.
    2. Paste the header into an online email header analyzer tool.
    3. These tools automatically parse the header and highlight potential issues.
    4. Common analyzers include MXToolbox, Google Admin Toolbox Messageheader, and others.
    5. They can quickly show IP locations, SPF/DKIM/DMARC results, and path analysis.
    6. Look for warnings or red flags flagged by the analyzer.
    7. IP reputation checks are often integrated into these tools.
    8. You can check the blacklisting status of originating IP addresses.
    9. Compare the domain's DNS records with the information in the header.
    10. These tools simplify the complex header data into understandable reports.
    11. They can identify sender spoofing by comparing different fields.
    12. Some analyzers offer malware scanning integration.
    13. Use the tool to trace the mail route and identify suspicious servers.
    14. You can verify the validity of DKIM signatures through these analyzers.
    15. If the email claims to be from a particular service, use the tool to see if the authentication checks align.
    16. These tools act as a second pair of eyes for header analysis.
    17. Be sure to use reputable and well-known header analyzer services.
    18. The results from these tools should be cross-referenced with your own understanding of email headers.
    19. Some advanced tools can even identify subtle signs of email manipulation.
    20. Ultimately, these external resources empower you to make more informed decisions about email safety.

    Mastering how to analyze email headers for phishing is an invaluable skill in your cybersecurity toolkit. While it might seem a bit technical at first, by focusing on key elements like the originating IP address, sender authentication, and the 'Received' path, you can uncover many fraudulent attempts. Remember, legitimacy often lies in the details that are hidden within the email's header information. By taking a few extra moments to inspect these headers, especially for suspicious emails, you significantly reduce your risk of falling victim to phishing scams and help keep your personal and professional data secure.

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