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<!DOCTYPE concept
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-42833109-F8C2-57FC-9995-0461698A19FF" xml:lang="en"><title>IMAP4
Concepts</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>This section describes the Internet Message Access Protocol (IMAP4) and
its implementation on the Symbian platform. </p>
<section id="GUID-DBF1C87D-7360-54B7-8658-B6659BF77F06-GENID-1-10-1-17-1-1-6-1-5-1-4-1-2-2"><title>IMAP4 protocol</title> <p>IMAP4
is one of the most common Internet standard protocols for retrieving emails.
It is an application layer Internet protocol operating on port 143 that allows
a local client to access email on a remote server. </p> <p>The current version,
IMAP version 4 revision 1 (IMAP4rev1), is defined by RFC 3501. Eariler, IMAP4
was called Internet Mail Access Protocol, Interactive Mail Access Protocol
(RFC 1064), and Interim Mail Access Protocol. </p> <p>The default port for
IMAP4 to download messages is 143, but if a client establishes a secure connection
(over SSL or TLS) for IMAP4 to download message, the port is 993. </p> <p>Most
email clients support either POP3 or IMAP to retrieve messages; however, few
Internet Service Providers (ISPs) support IMAP. IMAP4 supports access to the
mail store in both modes of operation—connected (online) and disconnected
(offline). </p> <p>Emails are generally sent to an email server that stores
received messages in the recipient's email mailbox. The user later retrieves
these messages with either a web browser or an email client that uses one
of a number of email retrieval protocols. </p> <p>Email clients using IMAP4
generally stores messages on the server until the user explicitly deletes
them. This allows multiple clients to access the same mailbox. However, the
client may store local copies of the messages, but these are considered to
be a temporary cache; the server's store is authoritative. </p> </section>
<section id="GUID-6162DB96-ED81-4AA4-B737-8298DC0A94D1"><title>Symbian platform implementation of IMAP4</title> <p>The Messaging
Application module has implemented all the functionality of standard IMAP4
and conforms to RFC3501. </p> </section>
<section id="GUID-572840C2-0ECC-4925-A42D-093E0043E07F"><title>IMAP4 example</title> <p>For more details on implementing
the IMAP4 MTM functions, see <xref href="GUID-D73AD200-BE4D-50BF-BCF9-14627DE530B7.dita">example
code</xref>. </p> </section>
</conbody><related-links>
<link href="GUID-1F755804-70D6-5635-B2F7-06F03C8D4B74.dita"><linktext>IMAP4 MTM</linktext>
</link>
</related-links></concept>