Header / Email header

An email header is a snippet of code that always precedes the email bodyt. It contains information about an email and its journey from the sender to the recipient and valuable feedback about the sender’s deliverability, including the following:

• Sender’s email address

• Recipient’s email address

• Server details

• Authentication details

• Errors (if any) encountered along the way

Email headers provide information that helps inbox service providers (ISPs) identify potential spam.