Posted On:email header Archives - Emailexplained.com
An email header is a block of text above the message body of an email. Headers contain information about the message including the sender, recipient, date, and subject, the servers that handled the email as it moved from the sender to the recipient, and time stamps for each server gone through.
An email may have to go through more than one Mail Transfer Agent (MTA) before reaching the final destination. Each time one MTA receives and forwards the email, it adds its own time and date stamp, IP address and other values, giving the mail multiple header lines. These, however, are usually not displayed but provide important information when, for example, trying to track and stop spam.
Headers also indicate information to use in DomainKeys Identified Mail (DKIM) for security reasons.