Electronic mail system is an application which allows the user to transfer or share an email from one computing system to another and is also called as the email system. It responds to the service generated by the user and is commonly used for transferring large amount of emails to local centers for purposes like enveloping and delivery. There are six major components of email system and their names are: Post Office Service System, Mail Transport System, Mail Routing System, Directory Service System, Administration Service System and External Gateways.