TCP/IP Email
Email is one of the most important uses of TCP/IP.
You Don't
When you write an email, you don't use TCP/IP.
When you write an email, you use an email program like Lotus Notes, Microsoft
Outlook or Netscape Communicator.
Your Email Program Does
Your email program uses different TCP/IP protocols:
- It sends your emails using SMTP
- It can download your emails from an email server using POP
- It can connect to an email server using IMAP
SMTP - Simple Mail Transfer Protocol
The SMTP protocol is used for the transmission of e-mails. SMTP takes care of
sending your email to another computer.
Normally your email is sent to an email server (SMTP server), and then to
another server or servers, and finally to its destination.
SMTP can only transmit pure text. It cannot transmit binary data like pictures, sounds or
movies.
SMTP uses the MIME protocol to send binary data across TCP/IP networks. The
MIME protocol converts binary data to pure text.
POP - Post Office Protocol
The POP protocol is used by email programs (like Microsoft Outlook) to
retrieve emails from an email server.
If your email program uses POP, all your emails are downloaded to your email
program (also called email client), each time it connects to your email server.
IMAP - Internet Message Access Protocol
The IMAP protocol is used by email programs (like Microsoft Outlook) just
like the POP protocol.
The main difference between the IMAP protocol and the POP protocol is that
the IMAP protocol will not automatically download all your emails each time your
email program connects to your email server.
The IMAP protocol allows you to look through your email messages at the email
server before you download them. With IMAP you can choose to download your
messages or just delete them. This way IMAP is perfect if you need to connect to
your email server from different locations, but only want to download your
messages when you are back in your office.
| 
