How to do Email Analysis ? Complete Guide

Despite advances in secure email gateways, cyberactors continue to bypass filters by abusing trust, misusing legitimate infrastructure, and creating messages that appear to be routine to recipients. This makes it all the more important for security teams to conduct regular email analysis.

It’s important to understand that the exercise of examining email messages doesn’t depend on whether a message “appears” or “feels” suspicious. It’s rather a structured investigation that checks email authentication results, sender identity, routing paths, message content, and attachments to categorize an email as “legitimate” or “malicious.” When done correctly, email analysis helps organizations detect threats early, limit internal spread, and respond with confidence instead of guesswork.

This guide breaks down email analysis step by step, explaining how to examine headers, interpret authentication signals, analyse email content, and take appropriate action using evidence-driven methods rather than assumptions.

What is Email Analysis

Email analysis is the process of examining an email to determine the legitimacy of the sender and the safety of the content and attachments. Instead of focusing on opens or clicks, security-driven email analysis examines technical details such as sender identity, headers, domains, links, attachments, and authentication results.

The goal of this email examination exercise is to detect phishing, spoofing, malware, or business email compromise (BEC) attempts before they cause damage.

The analysis can be done manually by reviewing email headers and content; however, the approach is slow and error-prone, especially when dealing with a large number of emails. That’s why there are several email analysis tools that automatically break down headers, check SPF, DKIM, and DMARC alignment, scan URLs and attachments, and highlight suspicious patterns. By using structured analysis rather than gut instinct, security teams can quickly determine whether an email is safe, risky, or outright malicious.

Email Analysis Process: From Collection to Response

The following process ensures that decisions are based on evidence rather than assumptions and that responses are consistent across incidents.

Step 1: Define the Objective of the Analysis

Before you analyse an email, you need to be clear about why you are analysing it. The objective could be to confirm whether an email is phishing, understand how it bypassed filters, or assess whether other users are at risk. Defining this upfront helps narrow the scope and prevents unnecessary checks that slow down the investigation. Clear objectives also help determine which email analysis tools to use and which indicators matter most for the situation.

Step 2: Collect the Email Data

Once the objective is clear, the next step is to collect the full email data. This usually includes the complete email headers, body content, links, and any attachments. Relying only on screenshots or forwarded messages can hide critical details, so it is important to work with the original message whenever possible. Most email analysis tools require raw headers or full message files to provide accurate results.

Step 3: Prepare the Email for Analysis

Before diving into technical checks, the email data needs to be cleaned and organized. This involves separating headers from content, identifying the sender and recipient details, and noting any obvious anomalies. Duplicate or irrelevant information should be set aside so the focus remains on the indicators that matter.

Tools like the Email Header Analyzer help simplify this step by automatically parsing complex headers into readable sections. This preparation makes it easier to analyse the email logically instead of jumping between scattered fields.

Step 4: Analyse the Email Using Technical and Contextual Signals

This is where most of the investigation happens. Using email analysis tools, analysts review authentication results such as SPF and DKIM, inspect sender domains, examine links and attachments, and trace the email’s delivery path. At the same time, contextual signals, like unusual requests or unexpected timing, are considered.

Step 5: Identify Risks and Key Findings

After reviewing the data, the next step is identifying what stands out. This could be a failed authentication check, a mismatched domain, a suspicious redirect link, or an attachment with unsafe characteristics. These findings help determine whether the email is malicious, suspicious, or legitimate. Clear documentation of these risks is important for both response and future reference.

Step 6: Decide on Action and Response

Based on the findings, teams decide what action is required. This might include quarantining similar emails, blocking sender domains, warning users, or escalating the incident for deeper investigation. Email analysis tools often help automate parts of this step by flagging related messages across mailboxes. The goal is not just to analyse an email, but to act on the analysis quickly and correctly.

Step 7: Review, Learn, and Improve

Examining suspicious emails does not end with one investigation. Reviewing outcomes helps teams understand what worked, what was missed, and how to detect future emails faster. Over time, this feedback loop improves detection rules, user awareness, and overall email security posture. This continuous improvement is what turns email analysis from a reactive task into a proactive security capability.

Why Email Analysis Is Important for Security Teams

Email analysis matters because one missed email is often all an attacker needs. Here are the main benefits you can reap from regularly inspecting all the emails:

Early Detection of Phishing and Malicious Emails

One of the biggest advantages of email analysis is catching threats before someone clicks, replies, or downloads anything. Many phishing and spoofing emails are designed to look normal at first glance. The branding looks right, the language sounds familiar, and nothing immediately feels off. Email inspection helps security teams look past appearances and focus on technical signals.

By analysing sender identity, authentication results, links, and attachments, teams can spot inconsistencies that users might miss. This early visibility is critical for stopping attacks such as credential harvesting and business email compromise at the earliest stage, before real damage occurs.

Reduced Risk of Internal Email Spread

Once an attacker gains access or convinces a user to engage, similar messages are often sent to others inside the organization. Email analysis helps security teams track how widely a suspicious message has spread and identify related emails across multiple users.

By finding and removing these emails early, teams can prevent further exposure. This limits lateral movement, reduces the number of affected users, and keeps a small incident from turning into a larger internal security problem.

Improved Visibility Into Sender and Domain Trust

Over time, consistent email reviewing builds a clearer picture of which senders and domains can be trusted. Authentication results, domain reputation, and sending patterns reveal whether an email truly comes from who it claims to be. This is especially important for detecting impersonation attempts that mimic vendors, executives, or internal teams.

Instead of relying on users to judge email legitimacy, organizations can use technical signals to make informed trust decisions. This reduces human error and creates a more reliable way to assess incoming messages.

Stronger Compliance and Security Accountability

Email analysis also plays an important role in compliance and governance. Organizations often need to show that they are actively monitoring email risks, especially when sensitive data is involved. Analysis logs, reports, and investigation records provide proof that security controls are in place and working.

This documentation helps during audits and incident reviews. It demonstrates that email risks are being actively managed, not ignored, and that the organization takes responsibility for protecting its communication channels.

Important Fields of an Email Header

Before you learn to analyse an email, you must understand the important fields included in an email header. Without that, you might not be able to make complete sense of the examination. Here are the fields:

• SPF (Sender Policy Framework): SPF shows whether the sending mail server is authorized to send emails for a domain. It compares the sender’s IP address against the domain’s SPF record published in DNS. An SPF failure does not always indicate that an email is malicious, but it is an important red flag that should be reviewed alongside DKIM and DMARC results.

• DKIM (DomainKeys Identified Mail): DKIM confirms that the email was sent by the claimed domain and that its content was not altered during transit. It uses cryptographic signatures added by the sender’s mail server and verified using a public key stored in DNS. A valid DKIM signature increases confidence in the email’s authenticity.

• MIME (Multipurpose Internet Mail Extensions): MIME defines how an email is structured and how different content types, such as text, images, and attachments, are included in a single message. It helps email clients understand how to display the message properly and how to handle attachments.

• Character Encoding (for example, ISO-8859-1): Character encoding tells email clients how to display letters and symbols correctly. Older encodings like ISO-8859-1 are still seen in some emails and can sometimes indicate legacy systems or unusual message formatting.

• SMTP and ESMTP: SMTP is the protocol used to send emails between mail servers. ESMTP is an extended version that supports additional features such as larger messages and attachments. These fields help trace how an email moved from the sender’s server to the recipient’s server.

• ESMTP ID: The ESMTP ID is a unique identifier assigned to an email during transmission. It acts like a tracking number and helps administrators trace delivery issues or investigate suspicious email activity across mail servers.

• CC and BCC: CC shows recipients who received a visible copy of the email, while BCC hides recipient details from others. In security analysis, unusual or unexpected BCC usage can sometimes indicate phishing or bulk distribution attempts.

• MUA (Mail User Agent): The MUA refers to the email client used to send or receive the message, such as Gmail, Outlook, or Apple Mail. This field provides context about how the email was composed and accessed.

• MTA (Mail Transfer Agent): MTAs are responsible for routing emails between servers. Examples include Postfix and Microsoft Exchange. Reviewing MTA details helps analysts understand the email’s delivery path.

• MDA (Mail Delivery Agent): The MDA handles the final step of delivering the email into the recipient’s mailbox. It helps confirm where and how the email was ultimately stored after transmission.

A General Check-List for Email Body Analysis

Email body analysis is for the visible part of the email, like the text, tone, and attachments. While attackers are becoming more sophisticated in their techniques, it’s still a good habit to use this checklist to systematically investigate all incoming emails and identify red flags. 

Check the Sender’s Email Address

Start by closely examining the sender’s email address, not just the display name. Phishing emails often use addresses that look legitimate at first glance but include subtle misspellings, extra characters, or unusual domains. Emails claiming to represent an organization but sent from personal email providers like Gmail or Yahoo should always be treated with caution.

Look for Generic or Impersonal Greetings

Legitimate organizations usually personalize their emails using your name or relevant account details. Phishing emails often rely on generic greetings such as “Dear Customer,” “Hello,” or no greeting at all. While this alone does not confirm malicious intent, it is an important signal when combined with other indicators.

Watch for Urgent or Threatening Language

Emails that create a sense of urgency are designed to push recipients into acting without thinking. Common examples include warnings about account suspension, payment failures, or security alerts that demand immediate action. Attackers use fear and pressure to bypass rational decision-making.

Be Cautious of Unusual Requests from Co-workers or Executives

Emails that appear to come from colleagues or senior executives but request sensitive information or urgent financial actions are a common tactic in business email compromise attacks. Requests for gift cards, wire transfers, or confidential data should always be verified through a separate communication channel.

Identify Gift, Reward, or Shipment Lures

Promises of free gifts, rewards, or prizes are frequently used to lure recipients into clicking on malicious links. Similarly, fake shipping notifications from well-known brands often ask users to confirm delivery details or payment information. Legitimate companies rarely request sensitive details through unsolicited emails.

You can use Phishing Link Checker to detect malicious links in emails and other online content. 

Review Spelling, Grammar, and Writing Style

Poor spelling and grammar can be a sign of phishing, though this indicator is becoming less reliable as AI-generated content becomes more prevalent. A sudden change in writing style, tone, or formatting compared to previous legitimate emails from the same sender can still be a useful clue.

Inspect Attachments Carefully

Attachments are a common delivery method for malware and credential-stealing attacks. Be cautious of unexpected invoices, receipts, or documents related to services you did not request. Pay special attention to QR codes or image-based attachments that hide clickable links, as these are often used to bypass traditional filters.

Final Thoughts: Turning Email Analysis Into Actionable Security

Email analysis is no longer optional. It is a basic requirement for protecting organizations from phishing, spoofing, malware, and business email compromise. As attacks become more advanced, it is no longer enough to rely solely on how an email looks or on user judgment. A structured review of headers, authentication results, links, and attachments helps security teams spot threats early and respond with confidence.

EasyDMARC makes email analysis easier by providing dedicated tools to inspect email headers, verify authentication, and quickly identify suspicious patterns. Start using EasyDMARC and get a clearer view of your email security with a 14-day free trial.