Different SMTP&IMAP and POP3

what is SMTP ?

• it stands for Simple Mail Transfer Protocol.
• RFC 2821.
• It is a TCP/IP protocol that specifies how computers exchange electronic mail. It works with post office protocol (POP).
• Transfers messages from sender’s mail server to recipient’s mail server.
• Push protocol, not a pull protocol.
• SMTP is a Principle Application Layer.
• Push (from client to server or server to server).
• Pull (from server to client).
• Email server port is a 25.
• SMTP server have database with user’s email address, linked to the to the DNS.
• To know more about SMTP please check Wikipedia link Click here .

What is POP3 ?

• it stands for Post Office Protocol third.
• RFC 1939.
• POP3 is simple and limited in functionality.
• Uses TCP port 110.
• To know more about POP please check Wikipedia link Click here.

Download and delete mode

• Retrieves messages on server and store the locally
• Delete messages on server

Problem

• Difficult to access email from multiple computers – work and home.
• Some email may have already been downloaded on another computer (work) – download-and-delete.
• To read email from another computer, must leave on server-download-and-keep
• Does not provide means for user to create remote folders on mail server

What is IMAP ?

• it stands for Internet Message Access Protocol.
• Another mail access protocol is Internet Mail Access Protocol (IMAP).
• IMAP is similar to POP3.
• IMAP is more powerful and more complex.
• RFC 2060.
• Mail not downloaded, but kept on server.
• Received email is associated with user’s INBOX.
• Users can create and manage remote folders.
• Users can retrieve portions of the email
  • Message header: Subject line and Sender
• To know more about IMAP please check Wikipedia link Click here