SMTP

• SMTP is an application layer protocol. The client who wants to send the mail opens a TCP connection to the SMTP server and then sends the mail across the connection.
• The SMTP server is always on listening mode. After successfully establishing the TCP connection the client process sends the mail instantly.

  The SMTP model is of two type :

1.end-to- end method. 

2.Store-and- forward method.

The end to end model is used to communicate between different organizations whereas the store and forward method are used within an organization. 

Advantages of SMTP. 

• Simple to use. 
• Quick email delivery. 
• Reliability.