TCP/IP Email
Email is one of the most important applications of TCP/IP.
You Don't Use...
When you write an email, you don't use TCP/IP.
When you write an email, you use an email program, such as Lotus Notes, Microsoft Outlook, or Netscape Communicator, among others.
Email Programs Use...
Your email program uses different TCP/IP protocols:
- Uses SMTP to send emails
- Uses POP to download emails from the mail server
- Uses IMAP to connect to the mail server
SMTP - Simple Mail Transfer Protocol
The SMTP protocol is used for transmitting emails. SMTP is responsible for sending emails to another computer.
Typically, emails are sent to a mail server (SMTP server), then to another (or several) server(s), and finally to their destination.
SMTP can also transmit plain text, but it cannot transmit binary data such as images, sounds, or movies.
SMTP uses the MIME protocol to send binary data over TCP/IP networks. The MIME protocol converts binary data into 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, once it connects to the mail server, all your emails are downloaded to the email program (or email client).
IMAP - Internet Message Access Protocol
Similar to POP, the IMAP protocol is also used by email programs.
The main difference between IMAP and POP is that if IMAP connects to the mail server, it does not automatically download the emails to the email program.
IMAP allows you to view emails on the server before downloading them. With IMAP, you can choose to download the 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 is very useful in this scenario.