TCP/IP Email

Email is one of the most important applications of TCP/IP.

You will not use...

When you write an email, you will not use TCP/IP.

When you write an email, you use an email program, such as Lotus Software's Notes, Microsoft's Outlook, or Netscape Communicator, etc. (Members of CodeW3C all prefer to use the famous Foxmail.)

The email program will use...

Your email program uses different TCP/IP protocols:

  • Send emails using SMTP
  • Download emails from the mail server using POP
  • Connect to the mail server using IMAP

SMTP - Simple Mail Transfer Protocol

The SMTP protocol is used to transmit email. SMTP is responsible for sending emails to another computer.

In most cases, emails are sent to a mail server (SMTP server), then sent to another (or several) servers, and finally delivered to their destination.

SMTP can also transmit plain text, but cannot transmit binary data such as images, sounds, or movies.

SMTP sends binary data through TCP/IP networks using MIME protocol. MIME protocol will convert binary data to plain text.

POP - Post Office Protocol

The POP protocol is used by email programs to retrieve emails from the mail server.

If your email program uses POP, then once it connects to the mail server, all your emails will be downloaded to the email program (or called an email client).

IMAP - Internet Message Access Protocol

Similar to POP, the IMAP protocol is also used by email programs.

The main difference between the IMAP protocol and the POP protocol is that if the IMAP is connected to the mail server, it will not automatically download the emails to the email program.

IMAP allows you to view emails on the mail server side before downloading them. With IMAP, you can choose to download these emails or simply delete them. For example, if you need to access the mail server from different locations but only want to download emails when you return to the office, IMAP will be very useful in this case.