IMAP是縮寫為Internet郵件存取協定。這是一個應用層網際網路協定，它允許電子郵件用戶端來存取郵件的遠端伺服器上的郵件。 IMAP伺服器通常監聽眾所周知的埠143。 IMAP通過SSL（IMAPS）被分配為埠號993。
IMAP支援兩種操作線上和離線模式。使用IMAP電子郵件用戶端一般在伺服器上保留郵件，直到使用者顯式刪除它們。
包裝com.sun.mail.imap是IMAP協定提供JavaMail API，它提供了存取一個IMAP郵件儲存。下表列出了此提供程式的介面和類：
| 類/介面 | 描述 |
|---|---|
| IMAPFolder.ProtocolCommand | This a simple interface for user-defined IMAP protocol commands. |
| ACL | This is a class. An access control list entry for a particular authentication identifier (user or group). |
| IMAPFolder | This class implements an IMAP folder. |
| IMAPFolder.FetchProfileItem | This a class for fetching headers. |
| IMAPMessage | This class implements an ReadableMime object. |
| IMAPMessage.FetchProfileCondition | This class implements the test to be done on each message in the folder. |
| IMAPSSLStore | This class provides access to an IMAP message store over SSL. |
| IMAPStore | This class provides access to an IMAP message store. |
| Rights | This class represents the set of rights for an authentication identifier (for instance, a user or a group). |
| Rights.Right | This inner class represents an individual right. |
| SortTerm | A particular sort criteria, as defined by RFC 5256. |
有幾點要注意此提供以上：
提供同時支援IMAP4和的IMAP4rev1協定。
關連IMAPStore維護IMAP協定的物件池在與IMAP伺服器進行通訊的使用。為檔案夾被開啟，需要有新的IMAP協定的物件，如果沒有可用，IMAPStore將為他們提供從連線池中，或者建立他們。當一個檔案夾被關閉，其IMAP協定的物件被返回到連線池，如果池有建立過的物件。
該連線IMAPStore物件可能會或可能不會維持一個單獨的IMAP協定的物件，它提供了儲存專用連線到IMAP伺服器。
IMAP協定提供程式支援以下屬性，這些屬性可以在JavaMail對談物件進行設定。該屬性始終設定為字串;型別列描述字串是如何解釋的。
| 名稱 | 型別 | 描述 |
|---|---|---|
| mail.imap.user | String | Default user name for IMAP. |
| mail.imap.host | String | The IMAP server to connect to. |
| mail.imap.port | int | The IMAP server port to connect to, if the connect() method doesn't explicitly specify one. Defaults to 143. |
| mail.imap.partialfetch | boolean | Controls whether the IMAP partial-fetch capability should be used. Defaults to true. |
| mail.imap.fetchsize | int | Partial fetch size in bytes. Defaults to 16K. |
| mail.imap.ignorebodystructuresize | boolean | The IMAP BODYSTRUCTURE response includes the exact size of each body part. Normally, this size is used to determine how much data to fetch for each body part. Defaults to false. |
| mail.imap.connectiontimeout | int | Socket connection timeout value in milliseconds. Default is infinite timeout. |
| mail.imap.timeout | int | Socket I/O timeout value in milliseconds. Default is infinite timeout. |
| mail.imap.statuscachetimeout | int | Timeout value in milliseconds for cache of STATUS command response. Default is 1000 (1 second). Zero disables cache. |
| mail.imap.appendbuffersize | int | Maximum size of a message to buffer in memory when appending to an IMAP folder. |
| mail.imap.connectionpoolsize | int | Maximum number of available connections in the connection pool. Default is 1. |
| mail.imap.connectionpooltimeout | int | Timeout value in milliseconds for connection pool connections. Default is 45000 (45 seconds). |
| mail.imap.separatestoreconnection | boolean | Flag to indicate whether to use a dedicated store connection for store commands. Default is false. |
| mail.imap.auth.login.disable | boolean | If true, prevents use of the non-standard AUTHENTICATE LOGIN command, instead using the plain LOGIN command. Default is false. |
| mail.imap.auth.plain.disable | boolean | If true, prevents use of the AUTHENTICATE PLAIN command. Default is false. |
| mail.imap.auth.ntlm.disable | boolean | If true, prevents use of the AUTHENTICATE NTLM command. Default is false. |
| mail.imap.proxyauth.user | String | If the server supports the PROXYAUTH extension, this property specifies the name of the user to act as. Authenticate to the server using the administrator's credentials. After authentication, the IMAP provider will issue the PROXYAUTH command with the user name specified in this property. |
| mail.imap.localaddress | String | Local address (host name) to bind to when creating the IMAP socket. Defaults to the address picked by the Socket class. |
| mail.imap.localport | int | Local port number to bind to when creating the IMAP socket. Defaults to the port number picked by the Socket class. |
| mail.imap.sasl.enable | boolean | If set to true, attempt to use the javax.security.sasl package to choose an authentication mechanism for login. Defaults to false. |
| mail.imap.sasl.mechanisms | String | A space or comma separated list of SASL mechanism names to try to use. |
| mail.imap.sasl.authorizationid | String | The authorization ID to use in the SASL authentication. If not set, the authentication ID (user name) is used. |
| mail.imap.sasl.realm | String | The realm to use with SASL authentication mechanisms that require a realm, such as DIGEST-MD5. |
| mail.imap.auth.ntlm.domain | String | The NTLM authentication domain. |
| mail.imap.auth.ntlm.flags | int | NTLM protocol-specific flags. |
| mail.imap.socketFactory | SocketFactory | If set to a class that implements the javax.net.SocketFactory interface, this class will be used to create IMAP sockets. |
| mail.imap.socketFactory.class | String | If set, specifies the name of a class that implements the javax.net.SocketFactory interface. This class will be used to create IMAP sockets. |
| mail.imap.socketFactory.fallback | boolean | If set to true, failure to create a socket using the specified socket factory class will cause the socket to be created using the java.net.Socket class. Defaults to true. |
| mail.imap.socketFactory.port | int | Specifies the port to connect to when using the specified socket factory. Default port is used when not set. |
| mail.imap.ssl.enable | boolean | If set to true, use SSL to connect and use the SSL port by default. Defaults to false for the "imap" protocol and true for the "imaps" protocol. |
| mail.imap.ssl.checkserveridentity | boolean | If set to true, check the server identity as specified by RFC 2595. Defaults to false. |
| mail.imap.ssl.trust | String |
If set, and a socket factory hasn't been specified, enables use of a MailSSLSocketFactory. If set to "*", all hosts are trusted. If set to a whitespace separated list of hosts, those hosts are trusted. Otherwise, trust depends on the certificate the server presents. |
| mail.imap.ssl.socketFactory | SSLSocketFactory | If set to a class that extends the javax.net.ssl.SSLSocketFactory class, this class will be used to create IMAP SSL sockets. |
| mail.imap.ssl.socketFactory.class | String | If set, specifies the name of a class that extends the javax.net.ssl.SSLSocketFactory class. This class will be used to create IMAP SSL sockets. |
| mail.imap.ssl.socketFactory.port | int | Specifies the port to connect to when using the specified socket factory. If not set, the default port will be used. |
| mail.imap.ssl.protocols | string | Specifies the SSL protocols that will be enabled for SSL connections. The property value is a whitespace separated list of tokens acceptable to the javax.net.ssl.SSLSocket.setEnabledProtocols method. |
| mail.imap.starttls.enable | boolean | If true, enables the use of the STARTTLS command (if supported by the server) to switch the connection to a TLS-protected connection before issuing any login commands. Default is false. |
| mail.imap.starttls.required | boolean | If true, requires the use of the STARTTLS command. If the server doesn't support the STARTTLS command, or the command fails, the connect method will fail. Defaults to false. |
| mail.imap.socks.host | string | Specifies the host name of a SOCKS5 proxy server that will be used for connections to the mail server. |
| mail.imap.socks.port | string | Specifies the port number for the SOCKS5 proxy server. This should only need to be used if the proxy server is not using the standard port number of 1080. |
| mail.imap.minidletime | int | This property sets the delay in milliseconds. If not set, the default is 10 milliseconds. |
| mail.imap.enableimapevents | boolean | Enable special IMAP-specific events to be delivered to the Store's ConnectionListener. If true, unsolicited responses received during the Store's idle method will be sent as ConnectionEvents with a type of IMAPStore.RESPONSE. The event's message will be the raw IMAP response string. By default, these events are not sent. |
| mail.imap.folder.class | String | Class name of a subclass of com.sun.mail.imap.IMAPFolder. The subclass can be used to provide support for additional IMAP commands. The subclass must have public constructors of the form public MyIMAPFolder(String fullName, char separator, IMAPStore store, Boolean isNamespace) and public MyIMAPFolder(ListInfo li, IMAPStore store) |
一般情況下，應用程式應該不需要直接使用的類在這個包。相反，他們應該使用javax.mail包定義的API（和子包）。應用程式不應該興建IMAPStore或IMAPFolder 的直接範例。相反，他們應該使用Session方法getStore獲得適當的儲存物件，並從獲取檔案夾物件。
範例使用IMAP伺服器是體現在 限額管理.