Front cover - IBM Redbooks

262 Lotus Security Handbook
Content-Type: image/gif
Content-Transfer-Encoding: base64
Content-ID:
Content-Description:
[...JPEG data...]
Just about every e-mail client supports MIME, which enables them to send and
receive graphics, audio, and video files via the messaging infrastructure on the
Internet. In addition, as mentioned, MIME also supports messages in character
sets other than ASCII.
POP
POP and IMAP (which we cover next) are protocols that specify protocols for
accessing mail from an Internet mailbox or Post office.
The Post Office Protocol, Version 3 (POP3) is used to pick up e-mail across a
network. Not all computer systems that use e-mail are connected to the Internet
24 hours a day, 7 days a week. Some users dial into a service provider on an
as-needed basis, while others may be connected to a LAN with a permanent
connection but may not always be powered on.
In cases such as these, the e-mail addressed to the users on these systems is
sent to a central e-mail post office system where it is held for the user until they
can pick it up.
POP3 allows a user to log onto an e-mail post office system across the network.
The post office system authenticates the user using an ID and password, allows
mail to be downloaded, and optionally allows the user to delete the mail located
on the central post office system.
IMAP
IMAP4 (Internet Message Access Protocol, version 4; once known as the
Interactive Mail Access Protocol) is a newer protocol, used by e-mail clients to
retrieve e-mail messages from a mail server and work with the mailboxes on the
server.
The latest version, IMAP4, is similar to POP3 but offers additional and more
sophisticated features. With IMAP, for example, it is possible to work with the
e-mail on the server, and sort and manage the e-mail in server-side folders.
For more information about IMAP, see Stanford University's Web page at the
following URL:
http://www-camis.stanford.edu/projects/imap/ml/imap.html