How to read and understand email message header ?

someone who writes an email

An e-mail is a message sent from one computer or mobile phone to another over the Internet. Today, its usefulness in the world is well established.

A recent study indicates that there are approximately 4.15 billion email users worldwide. It is the most personal space you have on the internet and you can access it from anywhere in the world thanks to the internet. Generally, an email is composed of the content of the message and a header.

The header of the email is often invisible nevertheless contains a lot of information that is very important and essential to know.

1. Description of a mail header

A mail header is a register of technical information accessible to both the sender and the recipient. Thanks to the information in the header you can understand the procedure to follow to send an email. The header includes the sender data, the date and time of sending, the subject of the e-mail and the name of the recipient(s) of the message. Its visualization interface varies from one messaging software to another. 

2. Information present in the headers

Post ID

The message ID is the call sign that each message receives. This is the digital fingerprint of a message and is usually added by the mail server that sends your message on behalf of your email client such as Microsoft Outlook, Mozilla Thunderbird, Evolution (GNOME), Mail (Apple), Lotus Notes (IBM), Opera Mail, Foxmail, Mail (Microsoft). Using this unique identifier, the message can only be sent once.

Creation date

This is the exact date and time the email is sent. Email clients usually display this time in the following format: day, dd month, yyyy hh:mm:ss.


In this section, you will find the name and email address of the sender who sent the message.


This part contains the recipient's name and email address. If there are multiple recipients, each recipient's name and email address will appear in the Carbon Copy (CC) and Invisible Carbon Copy (CCI) fields.


This is the title of your email. It gives an overview of what your recipient will find in the content of your email.

Trace Route

This is a very important element that informs the email address to which the message will be sent in the event that the message does not arrive at its destination for one reason or another.


This is information related to all mail servers that are crossed by mail, sender server, intermediate servers and recipient server. It contains the name, addresses and date of the email processed by all the servers.


MIME Version or Multipurpose Internet Mail Extensions is used to send and receive different types of data files like photos, audio and video files online. This version is in the form of HTML language or plain text message. Nevertheless, you are not harnessed to master these procedures if you do not really know them.

Content type

This part is displayed when you have an image or a video in the different types of message content.


SPF is an email authentication standard designed to prevent spammers from sending messages on behalf of your domain.


DKIM is a standard email authentication method that adds a digital signature to outgoing messages. Servers that receive messages signed with DKIM can ensure that the messages are coming from the sender and not from someone impersonating them.


DMARC is an open email authentication protocol that protects the email chain at the domain level. It's a system that protects your domain against identity theft, phishing, and other cyber attacks.

3. Importance of this information

This different information is truly quality knowledge to master to better understand the different parts of an email header. Mail headers can help you prevent spam and phishing attacks. You have the possibility to see if the email is secure and if it has reached its recipient without error or modification. Securing your emails should be governed by authentication standards like SPF, DKIM, and DMARC.

4. Tools to analyze this information

Google Admin Toolbox

Google Admin Toolbox lets you check and correct your domain settings. It analyzes Simple Mail Transfer Protocol (SMTP) message headers to identify the cause of delivery delays. In this way, you can detect misconfigured servers and message routing problems. Note that the SMTP protocol is an internet language used by mail servers to send and receive emails.


MX Toolbox is a powerful tool that makes mail headers readable by analyzing them according to RFC 822. It is the portal with which you can configure DNS settings and the entire domain can check for errors and perform a full scan .

MailAuth Analyzer

MailAuth Analyzer is a handy tool for analyzing email headers. It's the perfect solution when you want to check your email protocols, as it allows you to send a blank email to an auto-generated address. This is to help you detect, analyze, and verify the compliance of your email authentication (DKIM, DMARC). It also highlights alignment issues with your emails.

Email message headers are essentially composed of information that provides information about both the sender and the recipient. You can rely on this data to understand the entire routing process of your emails and thus avoid unwanted emails or to identify a scam or malicious program sent by email. Thanks to the different email clients you have the possibility to access your emails.


Do not forget to read our article: How to get email headers in my email software?

Now that light has been shed on the information contained in email headers, you need to find out how to find them within your messaging platform!