Detailed concepts of the IMAP service

Do you understand the concepts related to IMAP? In general mail settings, we may encounter this setting. We need a system to understand this IMAP service. Now let's take a look at the specific definition. Internet Information Access Protocol (IMAP) is used to access the email and bulletin board information stored in the email server system. IMAP allows the user's email program to access the remote message storage just like operating the local system. You can remotely operate emails stored in the IMAP service system on a desktop without transmitting messages or documents between computers.

Creating a distributed email system involves multiple technologies and approaches: POP Post Office Protocol, DMSP hierarchical email system protocol, and IMAP Internet information access protocol ). Among the three, the POP protocol was first created and therefore most people know it. DMSP has better support for "connectionless" operations, but it is limited to a single application PCMAIL ); IMAP provides an extended set of POP and DMSP and supports three remote email access methods: offline, online, and connectionless.

In the online mode, the IMAP user does not need to receive emails from the shared server at a time and then delete the emails. IMAP uses the interactive client-server mode. Users can request the header or body of a specific email from the server, or request the server to search for mails meeting certain conditions. Emails in the inbox are marked with various status signs, such as "delete" or "replied", and they are retained until the user actually deletes them. In the IMAP system, users can remotely manage their mailboxes as locally. Based on the implementation of the IMAP client and the email system structure designed by the system administrator, you can save emails on a local machine or on a server, or select either of them.

The IMAP service includes a series of operations: create, delete, and rename a mailbox, check new mail, permanently delete mail, set and clear signs, analyze and search based on server and MIME, valid and have selected retrieval mail attributes, text and part of the content. IMAP allows you to access new or saved emails from multiple computers ). This feature is especially important for environments that ensure email reliability and use multiple computers at the same time.

IMAP4 is the latest version of IMAP. Its main features are as follows:

Fully compatible with Internet message standards, such as MIME;

Allow multiple computers to simultaneously access and manage emails;

Allow access through inefficient file access protocols;

Supports "online", "offline", and "connectionless" access methods;

Supports concurrent access to shared mailboxes;

Client software does not need to understand the file storage format on the server.

Protocol Structure

IMAP service commands:

APPEND	AUTHENTICATE	CAPABILITY	CHECK	CLOSE
COPY	CREATE	DELETE	DELETEACL	EXAMINE
EXPUNGE	FETCH	GETACL	GETQUOTA	GETQUOTAROOT
LIST	LISTRIGHTS	LOGIN	LOGOUT	LSUB
MYRIGHTS	NOOP	RENAME	SEARCH	SELECT
SETACL	SETQUOTA	STARTTLS	STATUS	STORE
SUBSCRIBE	UID	UNSELECT	UNSUBSCRIBE	X <atom>