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com.sun.mail.imap package
An IMAP protocol provider for the Jakarta Mail API
that provides access to an IMAP message store.
Both the IMAP4 and IMAP4rev1 protocols are supported.
Refer to
RFC 3501
for more information.
The IMAP protocol provider also supports many IMAP extensions (described below).
Note that the server needs to support these extensions (and not all servers do)
in order to use the support in the IMAP provider.
You can query the server for support of these extensions using the
{@link com.sun.mail.imap.IMAPStore#hasCapability IMAPStore hasCapability}
method using the capability name defined by the extension
(see the appropriate RFC) after connecting to the server.
UIDPLUS Support
The IMAP UIDPLUS extension
(RFC 4315)
is supported via the IMAPFolder methods
{@link com.sun.mail.imap.IMAPFolder#addMessages addMessages},
{@link com.sun.mail.imap.IMAPFolder#appendUIDMessages appendUIDMessages}, and
{@link com.sun.mail.imap.IMAPFolder#copyUIDMessages copyUIDMessages}.
MOVE Support
The IMAP MOVE extension
(RFC 6851)
is supported via the IMAPFolder methods
{@link com.sun.mail.imap.IMAPFolder#moveMessages moveMessages} and
{@link com.sun.mail.imap.IMAPFolder#moveUIDMessages moveUIDMessages}.
SASL Support
The IMAP protocol provider can use SASL
(RFC 4422)
authentication mechanisms on systems that support the
javax.security.sasl APIs.
The SASL-IR
(RFC 4959)
capability is also supported.
In addition to the SASL mechanisms that are built into
the SASL implementation, users can also provide additional
SASL mechanisms of their own design to support custom authentication
schemes. See the
Java SASL API Programming and Deployment Guide for details.
Note that the current implementation doesn't support SASL mechanisms
that provide their own integrity or confidentiality layer.
OAuth 2.0 Support
Support for OAuth 2.0 authentication via the
XOAUTH2 authentication mechanism is provided either through the SASL
support described above or as a built-in authentication mechanism in the
IMAP provider.
The OAuth 2.0 Access Token should be passed as the password for this mechanism.
See
OAuth2 Support for details.
Connection Pool
A connected IMAPStore maintains a pool of IMAP protocol objects for
use in communicating with the IMAP server. The IMAPStore will create
the initial AUTHENTICATED connection and seed the pool with this
connection. As folders are opened and new IMAP protocol objects are
needed, the IMAPStore will provide them from the connection pool,
or create them if none are available. When a folder is closed,
its IMAP protocol object is returned to the connection pool if the
pool is not over capacity.
A mechanism is provided for timing out idle connection pool IMAP
protocol objects. Timed out connections are closed and removed (pruned)
from the connection pool.
The connected IMAPStore object may or may not maintain a separate IMAP
protocol object that provides the store a dedicated connection to the
IMAP server. This is provided mainly for compatibility with previous
implementations of the IMAP protocol provider.
QUOTA Support
The IMAP QUOTA extension
(RFC 2087)
is supported via the
{@link javax.mail.QuotaAwareStore QuotaAwareStore} interface implemented by
{@link com.sun.mail.imap.IMAPStore IMAPStore}, and the
{@link com.sun.mail.imap.IMAPFolder#getQuota IMAPFolder getQuota} and
{@link com.sun.mail.imap.IMAPFolder#setQuota IMAPFolder setQuota} methods.
ACL Support
The IMAP ACL extension
(RFC 2086)
is supported via the
{@link com.sun.mail.imap.Rights Rights} class and the IMAPFolder methods
{@link com.sun.mail.imap.IMAPFolder#getACL getACL},
{@link com.sun.mail.imap.IMAPFolder#addACL addACL},
{@link com.sun.mail.imap.IMAPFolder#removeACL removeACL},
{@link com.sun.mail.imap.IMAPFolder#addRights addRights},
{@link com.sun.mail.imap.IMAPFolder#removeRights removeRights},
{@link com.sun.mail.imap.IMAPFolder#listRights listRights}, and
{@link com.sun.mail.imap.IMAPFolder#myRights myRights}.
SORT Support
The IMAP SORT extension
(RFC 5256)
is supported via the
{@link com.sun.mail.imap.SortTerm SortTerm} class and the IMAPFolder
{@link com.sun.mail.imap.IMAPFolder#getSortedMessages getSortedMessages}
methods.
CONDSTORE and QRESYNC Support
Basic support is provided for the IMAP CONDSTORE
(RFC 4551)
and QRESYNC
(RFC 5162)
extensions for the purpose of resynchronizing a folder after offline operation.
Of course, the server must support these extensions.
Use of these extensions is enabled by using the new
{@link com.sun.mail.imap.IMAPFolder#open(int,com.sun.mail.imap.ResyncData)
IMAPFolder open} method and supplying an appropriate
{@link com.sun.mail.imap.ResyncData ResyncData} instance.
Using
{@link com.sun.mail.imap.ResyncData#CONDSTORE ResyncData.CONDSTORE}
enables the CONDSTORE extension, which allows you to discover the
modification sequence number (modseq) of messages using the
{@link com.sun.mail.imap.IMAPMessage#getModSeq IMAPMessage getModSeq}
method and the
{@link com.sun.mail.imap.IMAPFolder#getHighestModSeq
IMAPFolder getHighestModSeq} method.
Using a
{@link com.sun.mail.imap.ResyncData ResyncData} instance with appropriate
values also allows the server to report any changes in messages since the last
resynchronization.
The changes are reported as a list of
{@link javax.mail.event.MailEvent MailEvent} instances.
The special
{@link com.sun.mail.imap.MessageVanishedEvent MessageVanishedEvent} reports on
UIDs of messages that have been removed since the last resynchronization.
A
{@link javax.mail.event.MessageChangedEvent MessageChangedEvent} reports on
changes to flags of messages.
For example:
Folder folder = store.getFolder("whatever");
IMAPFolder ifolder = (IMAPFolder)folder;
List<MailEvent> events = ifolder.open(Folder.READ_WRITE,
new ResyncData(prevUidValidity, prevModSeq));
for (MailEvent ev : events) {
if (ev instanceOf MessageChangedEvent) {
// process flag changes
} else if (ev instanceof MessageVanishedEvent) {
// process messages that were removed
}
}
See the referenced RFCs for more details on these IMAP extensions.
WITHIN Search Support
The IMAP WITHIN search extension
(RFC 5032)
is supported via the
{@link com.sun.mail.imap.YoungerTerm YoungerTerm} and
{@link com.sun.mail.imap.OlderTerm OlderTerm}
{@link javax.mail.search.SearchTerm SearchTerms}, which can be used as follows:
// search for messages delivered in the last day
Message[] msgs = folder.search(new YoungerTerm(24 * 60 * 60));
LOGIN-REFERRAL Support
The IMAP LOGIN-REFERRAL extension
(RFC 2221)
is supported.
If a login referral is received when connecting or when authentication fails, a
{@link com.sun.mail.imap.ReferralException ReferralException} is thrown.
A referral can also occur when login succeeds. By default, no exception is
thrown in this case. To force an exception to be thrown and the authentication
to fail, set the mail.imap.referralexception property to "true".
COMPRESS Support
The IMAP COMPRESS extension
(RFC 4978)
is supported.
If the server supports the extension and the
mail.imap.compress.enable property is set to "true",
compression will be enabled.
UTF-8 Support
The IMAP UTF8 extension
(RFC 6855)
is supported.
If the server supports the extension, the client will enable use of UTF-8,
allowing use of UTF-8 in IMAP protocol strings such as folder names.
Properties
The IMAP protocol provider supports the following properties,
which may be set in the Jakarta Mail Session object.
The properties are always set as strings; the Type column describes
how the string is interpreted. For example, use
props.put("mail.imap.port", "888");
to set the mail.imap.port property, which is of type int.
Note that if you're using the "imaps" protocol to access IMAP over SSL,
all the properties would be named "mail.imaps.*".
IMAP properties
Name
Type
Description
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.peek
boolean
If set to true, use the IMAP PEEK option when fetching body parts,
to avoid setting the SEEN flag on messages.
Defaults to false.
Can be overridden on a per-message basis by the
{@link com.sun.mail.imap.IMAPMessage#setPeek setPeek}
method on IMAPMessage.
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.
Some servers report this size incorrectly in some cases; this property can
be set to work around such server bugs.
If this property is set to true, this size is ignored and data is fetched
until the server reports the end of data.
This will result in an extra fetch if the data size is a multiple of the
block size.
Defaults to false.
mail.imap.connectiontimeout
int
Socket connection timeout value in milliseconds.
This timeout is implemented by java.net.Socket.
Default is infinite timeout.
mail.imap.timeout
int
Socket read timeout value in milliseconds.
This timeout is implemented by java.net.Socket.
Default is infinite timeout.
mail.imap.writetimeout
int
Socket write timeout value in milliseconds.
This timeout is implemented by using a
java.util.concurrent.ScheduledExecutorService per connection
that schedules a thread to close the socket if the timeout expires.
Thus, the overhead of using this timeout is one thread per connection.
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. If not set, or set to -1, there is no maximum and all messages
are buffered. If set to 0, no messages are buffered. If set to (e.g.)
8192, messages of 8K bytes or less are buffered, larger messages are
not buffered. Buffering saves cpu time at the expense of short term
memory usage. If you commonly append very large messages to IMAP
mailboxes you might want to set this to a moderate value (1M or less).
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.allowreadonlyselect
boolean
If false, attempts to open a folder read/write will fail
if the SELECT command succeeds but indicates that the folder is READ-ONLY.
This sometimes indicates that the folder contents can'tbe changed, but
the flags are per-user and can be changed, such as might be the case for
public shared folders. If true, such open attempts will succeed, allowing
the flags to be changed. The getMode method on the
Folder object will return Folder.READ_ONLY
in this case even though the open method specified
Folder.READ_WRITE. Default is false.
mail.imap.auth.mechanisms
String
If set, lists the authentication mechanisms to consider, and the order
in which to consider them. Only mechanisms supported by the server and
supported by the current implementation will be used.
The default is "PLAIN LOGIN NTLM", which includes all
the authentication mechanisms supported by the current implementation
except XOAUTH2.
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.auth.ntlm.domain
String
The NTLM authentication domain.
mail.imap.auth.ntlm.flags
int
NTLM protocol-specific flags.
See
http://curl.haxx.se/rfc/ntlm.html#theNtlmFlags for details.
mail.imap.auth.xoauth2.disable
boolean
If true, prevents use of the AUTHENTICATE XOAUTH2 command.
Because the OAuth 2.0 protocol requires a special access token instead of
a password, this mechanism is disabled by default. Enable it by explicitly
setting this property to "false" or by setting the "mail.imap.auth.mechanisms"
property to "XOAUTH2".
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.
Should not normally need to be set, but useful with multi-homed hosts
where it's important to pick a particular local address to bind to.
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.sasl.usecanonicalhostname
boolean
If set to true, the canonical host name returned by
{@link java.net.InetAddress#getCanonicalHostName InetAddress.getCanonicalHostName}
is passed to the SASL mechanism, instead of the host name used to connect.
Defaults to false.
mail.imap.sasl. xgwtrustedapphack.enable
boolean
If set to true, enables a workaround for a bug in the Novell Groupwise
XGWTRUSTEDAPP SASL mechanism, when that mechanism is being used.
Defaults to true.
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. Note that this is an
instance of a class, not a name, and must be set using the
put method, not the setProperty method.
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.
If not set, the default port will be used.
mail.imap.usesocketchannels
boolean
If set to true, use SocketChannels instead of Sockets for connecting
to the server. Required if using the IdleManager.
Ignored if a socket factory is set.
Defaults to false.
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.
These additional checks based on the content of the server's certificate
are intended to prevent man-in-the-middle attacks.
Defaults to false.
mail.imap.ssl.trust
String
If set, and a socket factory hasn't been specified, enables use of a
{@link com.sun.mail.util.MailSSLSocketFactory 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. Note that this is an
instance of a class, not a name, and must be set using the
put method, not the setProperty method.
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.ssl.ciphersuites
string
Specifies the SSL cipher suites that will be enabled for SSL connections.
The property value is a whitespace separated list of tokens acceptable
to the javax.net.ssl.SSLSocket.setEnabledCipherSuites 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.
If the server does not support STARTTLS, the connection continues without
the use of TLS; see the
mail.imap.starttls.required
property to fail if STARTTLS isn't supported.
Note that an appropriate trust store must configured so that the client
will trust the server's certificate.
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.proxy.host
string
Specifies the host name of an HTTP web proxy server that will be used for
connections to the mail server.
mail.imap.proxy.port
string
Specifies the port number for the HTTP web proxy server.
Defaults to port 80.
mail.imap.proxy.user
string
Specifies the user name to use to authenticate with the HTTP web proxy server.
By default, no authentication is done.
mail.imap.proxy.password
string
Specifies the password to use to authenticate with the HTTP web proxy server.
By default, no authentication is done.
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
Applications typically call the idle method in a loop. If another
thread termiantes the IDLE command, it needs a chance to do its
work before another IDLE command is issued. The idle method enforces
a delay to prevent thrashing between the IDLE command and regular
commands. This property sets the delay in milliseconds. If not
set, the default is 10 milliseconds.
mail.imap.enableresponseevents
boolean
Enable special IMAP-specific events to be delivered to the Store's
ConnectionListener. If true, IMAP OK, NO, BAD, or BYE responses
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.
NOTE: This capability is highly experimental and likely will change
in future releases.
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.
NOTE: This capability is highly experimental and likely will change
in future releases.
mail.imap.throwsearchexception
boolean
If set to true and a {@link javax.mail.search.SearchTerm SearchTerm}
passed to the
{@link javax.mail.Folder#search Folder.search}
method is too complex for the IMAP protocol, throw a
{@link javax.mail.search.SearchException SearchException}.
For example, the IMAP protocol only supports less-than and greater-than
comparisons for a {@link javax.mail.search.SizeTerm SizeTerm}.
If false, the search will be done locally by fetching the required
message data and comparing it locally.
Defaults to false.
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)
mail.imap.closefoldersonstorefailure
boolean
In some cases, a failure of the Store connection indicates a failure of the
server, and all Folders associated with that Store should also be closed.
In other cases, a Store connection failure may be a transient failure, and
Folders may continue to operate normally.
If this property is true (the default), failures in the Store connection cause
all associated Folders to be closed.
Set this property to false to better handle transient failures in the Store
connection.
mail.imap.finalizecleanclose
boolean
When the finalizer for IMAPStore is called,
should the connection to the server be closed cleanly, as if the
application called the close method?
Or should the connection to the server be closed without sending
any commands to the server?
Defaults to false, the connection is not closed cleanly.
mail.imap.referralexception
boolean
If set to true and an IMAP login referral is returned when the authentication
succeeds, fail the connect request and throw a
{@link com.sun.mail.imap.ReferralException ReferralException}.
Defaults to false.
mail.imap.compress.enable
boolean
If set to true and the IMAP server supports the COMPRESS=DEFLATE extension,
compression will be enabled.
Defaults to false.
mail.imap.compress.level
int
The compression level to be used, in the range -1 to 9.
See the {@link java.util.zip.Deflater Deflater} class for details.
mail.imap.compress.strategy
int
The compression strategy to be used, in the range 0 to 2.
See the {@link java.util.zip.Deflater Deflater} class for details.
mail.imap.reusetagprefix
boolean
If true, always use "A" for the IMAP command tag prefix.
If false, the IMAP command tag prefix is different for each connection,
from "A" through "ZZZ" and then wrapping around to "A".
Applications should never need to set this.
Defaults to false.
In general, applications should not need to use the classes in this
package directly. Instead, they should use the APIs defined by the
javax.mail package (and subpackages). Applications should
never construct instances of IMAPStore or
IMAPFolder directly. Instead, they should use the
Session method getStore to acquire an
appropriate Store object, and from that acquire
Folder objects.
Loggers
In addition to printing debugging output as controlled by the
{@link javax.mail.Session Session} configuration,
the com.sun.mail.imap provider logs the same information using
{@link java.util.logging.Logger} as described in the following table:
IMAP Loggers
Logger Name
Logging Level
Purpose
com.sun.mail.imap
CONFIG
Configuration of the IMAPStore
com.sun.mail.imap
FINE
General debugging output
com.sun.mail.imap.connectionpool
CONFIG
Configuration of the IMAP connection pool
com.sun.mail.imap.connectionpool
FINE
Debugging output related to the IMAP connection pool
com.sun.mail.imap.messagecache
CONFIG
Configuration of the IMAP message cache
com.sun.mail.imap.messagecache
FINE
Debugging output related to the IMAP message cache
com.sun.mail.imap.protocol
FINEST
Complete protocol trace
WARNING
WARNING: The APIs unique to this package should be
considered EXPERIMENTAL. They may be changed in the
future in ways that are incompatible with applications using the
current APIs.