TCP/IP Email
Email is one of the most important applications of TCP/IP.
You won't use...
When you write an email, you won't use TCP/IP.
When you write an email, you use an email program, such as Lotus Notes, Microsoft Outlook, or Netscape Communicator, and so on.
What the email program will use...
Your email program uses different TCP/IP protocols:
- Use SMTP to send mail
- Use POP to download mail from a mail server
- Use IMAP to connect to a mail server
SMTP - Simple Mail Transfer Protocol
The SMTP protocol is used to transmit email. SMTP is responsible for sending mail to another computer.
Typically, mail is delivered to a mail server (SMTP server), then to another (or several) servers, and then finally delivered to its destination.
SMTP can also transmit plain text, but it cannot transmit binary data such as pictures, audio, 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 mail from a mail server.
If your email program uses POP, then once it connects to the mail server, all your mail will be downloaded to the email program (or what is 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: if IMAP connects to a mail server, it will not automatically download mail to the email program.
IMAP gives you the ability to view emails on the mail server 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 mail when you return to the office, IMAP is useful in this situation.
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