Email Header
The email header is a code snippet in an HTML email,
that contains information about the sender, recipient, email’s route to get to
the inbox and various authentication details. The email header always precedes
the email body.
Purpose
of email header:
- Providing information about the sender and
recipient. An email header tells who sent the email and where it
arrived. Some markers indicate this information, like “From:” sender’s
name and email address, “To:” the recipient’s name and email address, and
“Date:” the time and date of when the email was sent. All of these are
mandatory indicators. Other parts of the email header are optional and
differ among email service providers.
- Preventing spam. The information displayed
in the email header helps email service providers troubleshoot
potential spam issues. ESPs(email Service Providers) analyzes
the email header, the “Received:” tag, in particular, to decide whether to
deliver an email or not.
- Identifying the email route. When an email
is sent from one computer to another, it transfers through the Mail
Transfer Agent which automatically “stamps” the email with
information about the recipient, time and date in the email header.
Analyzing an Email Header
To analyze it, you need to find the email header and
examine the lines of interest to you. All the code from the beginning, until
the <body> tag, represents the header. Here is the list of what you can
find in the email header:
Received: lines. They
show the address of the computer that received the email, as well as other
computer’s addresses that an email may have been transferred through.
Unlike other email header elements, Received: lines can’t be forged.
MIME-version. Multipurpose
Internet Mail Extensions are an Internet standard that extends the format of
email by supporting text and non-text attachments like audio, video, images,
message bodies with multiple parts, etc.
Message-ID. The
message-ID is a globally unique identifier used in email. Message-IDs have a
specific format that is generated for a specific email address and
message, thus, no two messages have the same Message-ID.
DKIM Signatures. DomainKeys
Identified Mail confirms the sender’s authenticity by connecting the
domain name with the email. DKIM is the technology that helps to reduce spam
and phishing and allows companies to vouch for their email messages.
