There are 3 parts of an email: envelope of mail, header and the body of the mail.
A Email headers are a small part of html code which consist of all routing information of an email such as the sender, recipient, subject etc.
A header is the one who provides the route for the email from one computer to another.
Some key components of an email are:
· Messge id:
It is a identifier of the mail which is generated by mail server who is sending the mail.
It is the time at which the mail is created. It is a compulsory field in header.
It stores the sender mail address and is a compulsory field. It provides the information of the sender.
It is a compulsory field and store the email address of the recipient.
This field is used when you have to send your mail to more then one person.
This is the single text line which the recipient sees when receives the mail. It is not a compulsory field in the header
This header shows about the status of the mail in the SPF filter on the ip address.
This header shows the status of the mail from the DKIM filter on the basis of domain name.
This is the overall authentication system status which is done by taking SPF and DKIM in consideration.
Email header are used for the authentication of the mails by using the last three filters. It prevents the recipients from getting a spam mail.
You can view your header in gmail by pressing the “Show Original” button and it will give you a view of the original email header.