What Are Email Headers

Acquainting oneself with email headers is advantageous for initiating email campaigns and ensuring the authenticity of messages before interacting with any embedded links, thereby reducing the risk of falling victim to phishing attacks.

Email headers provide valuable insights into the necessary email security measures to be implemented in order to prevent messages from being flagged as spam. Conducting test emails and scrutinizing their headers enables the identification and implementation of appropriate security measures to enhance email deliverability and avoid potential issues with spam filters.

An email header comprises a code snippet containing crucial information for verifying the authenticity of an email message. Positioned before the email body, it encompasses vital details such as the sender's and recipient's information.

An email header goes beyond the basic "to," "from," "date," and "subject" sections that appear before the email body. It serves a crucial function in documenting the path of an email as it travels, as every email message contains an email header.

When an email is sent from one address to another, it passes through mail transfer agents (MTAs). Consequently, the email header reveals whether the email was sent to additional addresses prior to reaching its final destination. If the header information appears suspicious, users can exercise caution and refrain from interacting with the email.

Headers use metadata to provide information about the transmission process.

Example from Gmail

Understanding the Metadata

The metadata provides additional information about the trajectory a message has taken. Having a comprehension of these header lines will contribute to enhancing the security of your emails.

Every email header is different, and some metadata is optional. Here are some of the metadata tags you should know:

• From – contains information about the sender. Keep note that the name and email address can be forged by hackers.
• To – shows the name and email address of the recipient, including all of the email addresses on the CC (carbon copy) and BCC (blind carbon copy) fields.
• Subject – the title or the topic that the sender sets on the subject line.
• Return Path – required field which contains the address to which the systems sends back an email. If there is no reply-to, it will be used as the address for recipients to reply to as well.
• Reply-To – optional field which contains the address for recipients to reply to.
• Envelope-To – shows that an email was sent to the address on this line.
• Date – timestamp of when an email client sent an email, usually follows the format of day, dd month yyyy hh:mm:ss. For example, Wed, 16 Dec 2020 16:57:23.
• Received – shows a valid email address of the recipient that cannot be forged. It also shows all the addresses that the email passed through while being sent from one computer to another.
• DKIM signature and DomainKeys –the DomainKeys and DomainKeys Identified Mail (DKIM) signatures help email providers identify and authenticate emails by connecting the domain name with the email.
• Message-ID – a unique identifier of letters and numbers created when first writing an email. Even though no two messages have the same ID, this line is forgeable.
• MIME version – Multipurpose Internet Mail Extensions (MIME) version is an internet standard that extends an email’s format and functionality. An email can have videos, images, and other files attached because of MIME.
• Content-type – tells you whether the sender wrote the email as plain text or using HTML. It will also show when you have an image or video content.
• X-Spam-Status – Apache SpamAssassin feature. It tells you the spam score of an email and whether it has been marked as spam.
• X-Spam-Level – depends on the score of the email’s X-Spam-Status. For every point it gains, the X-Spam-Level will show one asterisk.
• Message body – shows the main content of an email.

While it is possible to use email without understanding the headers, having knowledge of them greatly enhances the security of your messages. The sender, recipient, and subject information contained in the email header empower users to:

1. Prevent malicious attacks: Understanding email headers helps protect your account from phishing and spam attacks. Email service providers can troubleshoot potential issues by analyzing the email header information.
2. Track email route: The data within the email header allows you to track the source of a message by retrieving the sender's IP address. This knowledge is valuable if you experience malicious attacks and wish to identify the attacker. By copying the full email header and using a trace email tool, you can trace the origin.
3. Create effective email campaigns: By checking the email header of your email campaign, you can avoid having your messages land in spam or junk folders. Sending a test email to yourself and examining the accuracy of the header information helps improve email deliverability.

Understanding email headers empowers you to protect against threats, track message origins, and optimize your email campaigns for successful delivery.

You can adjust, add headers to individual emails. Visit Groundhogg > Emails and select an email. Click the [ + ] button to add a header.