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com.sun.mail.smtp package
An SMTP protocol provider for the Jakarta Mail API
that provides access to an SMTP server.
Refer to RFC 821
for more information.
When sending a message, detailed information on each address that
fails is available in an
{@link com.sun.mail.smtp.SMTPAddressFailedException SMTPAddressFailedException}
chained off the top level
{@link javax.mail.SendFailedException SendFailedException}
that is thrown.
In addition, if the mail.smtp.reportsuccess property
is set, an
{@link com.sun.mail.smtp.SMTPAddressSucceededException
SMTPAddressSucceededException}
will be included in the list for each address that is successful.
Note that this will cause a top level
{@link javax.mail.SendFailedException SendFailedException}
to be thrown even though the send was successful.
The SMTP provider also supports ESMTP
(RFC 1651).
It can optionally use SMTP Authentication
(RFC 2554)
using the LOGIN, PLAIN, DIGEST-MD5, and NTLM mechanisms
(RFC 4616
and RFC 2831).
To use SMTP authentication you'll need to set the mail.smtp.auth
property (see below) or provide the SMTP Transport
with a username and password when connecting to the SMTP server. You
can do this using one of the following approaches:
-
Provide an Authenticator object when creating your mail Session
and provide the username and password information during the
Authenticator callback.
Note that the mail.smtp.user property can be set to provide a
default username for the callback, but the password will still need to be
supplied explicitly.
This approach allows you to use the static Transport send method
to send messages.
-
Call the Transport connect method explicitly with username and
password arguments.
This approach requires you to explicitly manage a Transport object
and use the Transport sendMessage method to send the message.
The transport.java demo program demonstrates how to manage a Transport
object. The following is roughly equivalent to the static
Transport send method, but supplies the needed username and
password:
Transport tr = session.getTransport("smtp");
tr.connect(smtphost, username, password);
msg.saveChanges(); // don't forget this
tr.sendMessage(msg, msg.getAllRecipients());
tr.close();
When using DIGEST-MD5 authentication,
you'll also need to supply an appropriate realm;
your mail server administrator can supply this information.
You can set this using the mail.smtp.sasl.realm property,
or the setSASLRealm method on SMTPTransport.
The SMTP protocol provider can use SASL
(RFC 2222)
authentication mechanisms on systems that support the
javax.security.sasl APIs, such as J2SE 5.0.
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.
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
SMTP provider.
The OAuth 2.0 Access Token should be passed as the password for this mechanism.
See
OAuth2 Support for details.
SMTP can also optionally request Delivery Status Notifications
(RFC 1891).
The delivery status will typically be reported using
a "multipart/report"
(RFC 1892)
message type with a "message/delivery-status"
(RFC 1894)
part.
You can use the classes in the com.sun.mail.dsn package to
handle these MIME types.
Note that you'll need to include dsn.jar in your CLASSPATH
as this support is not included in mail.jar.
See below for the properties to enable these features.
Note also that THERE IS NOT SUFFICIENT DOCUMENTATION HERE TO USE THESE
FEATURES!!! You will need to read the appropriate RFCs mentioned above
to understand what these features do and how to use them. Don't just
start setting properties and then complain to us when it doesn't work
like you expect it to work. READ THE RFCs FIRST!!!
The SMTP protocol provider supports the CHUNKING extension defined in
RFC 3030.
Set the mail.smtp.chunksize property to the desired chunk
size in bytes.
If the server supports the CHUNKING extension, the BDAT command will be
used to send the message in chunksize pieces. Note that no pipelining is
done so this will be slower than sending the message in one piece.
Note also that the BINARYMIME extension described in RFC 3030 is NOT supported.
Properties
The SMTP 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.smtp.port", "888");
to set the mail.smtp.port property, which is of type int.
Note that if you're using the "smtps" protocol to access SMTP over SSL,
all the properties would be named "mail.smtps.*".
SMTP properties
Name
Type
Description
mail.smtp.user
String
Default user name for SMTP.
mail.smtp.host
String
The SMTP server to connect to.
mail.smtp.port
int
The SMTP server port to connect to, if the connect() method doesn't
explicitly specify one. Defaults to 25.
mail.smtp.connectiontimeout
int
Socket connection timeout value in milliseconds.
This timeout is implemented by java.net.Socket.
Default is infinite timeout.
mail.smtp.timeout
int
Socket read timeout value in milliseconds.
This timeout is implemented by java.net.Socket.
Default is infinite timeout.
mail.smtp.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.smtp.from
String
Email address to use for SMTP MAIL command. This sets the envelope
return address. Defaults to msg.getFrom() or
InternetAddress.getLocalAddress(). NOTE: mail.smtp.user was previously
used for this.
mail.smtp.localhost
String
Local host name used in the SMTP HELO or EHLO command.
Defaults to InetAddress.getLocalHost().getHostName().
Should not normally need to
be set if your JDK and your name service are configured properly.
mail.smtp.localaddress
String
Local address (host name) to bind to when creating the SMTP 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.smtp.localport
int
Local port number to bind to when creating the SMTP socket.
Defaults to the port number picked by the Socket class.
mail.smtp.ehlo
boolean
If false, do not attempt to sign on with the EHLO command. Defaults to
true. Normally failure of the EHLO command will fallback to the HELO
command; this property exists only for servers that don't fail EHLO
properly or don't implement EHLO properly.
mail.smtp.auth
boolean
If true, attempt to authenticate the user using the AUTH command.
Defaults to false.
mail.smtp.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 "LOGIN PLAIN DIGEST-MD5 NTLM", which includes all
the authentication mechanisms supported by the current implementation
except XOAUTH2.
mail.smtp.auth.login.disable
boolean
If true, prevents use of the AUTH LOGIN command.
Default is false.
mail.smtp.auth.plain.disable
boolean
If true, prevents use of the AUTH PLAIN command.
Default is false.
mail.smtp.auth.digest-md5.disable
boolean
If true, prevents use of the AUTH DIGEST-MD5 command.
Default is false.
mail.smtp.auth.ntlm.disable
boolean
If true, prevents use of the AUTH NTLM command.
Default is false.
mail.smtp.auth.ntlm.domain
String
The NTLM authentication domain.
mail.smtp.auth.ntlm.flags
int
NTLM protocol-specific flags.
See
http://curl.haxx.se/rfc/ntlm.html#theNtlmFlags for details.
mail.smtp.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.smtp.auth.mechanisms"
property to "XOAUTH2".
mail.smtp.submitter
String
The submitter to use in the AUTH tag in the MAIL FROM command.
Typically used by a mail relay to pass along information about the
original submitter of the message.
See also the {@link com.sun.mail.smtp.SMTPMessage#setSubmitter setSubmitter}
method of {@link com.sun.mail.smtp.SMTPMessage SMTPMessage}.
Mail clients typically do not use this.
mail.smtp.dsn.notify
String
The NOTIFY option to the RCPT command. Either NEVER, or some
combination of SUCCESS, FAILURE, and DELAY (separated by commas).
mail.smtp.dsn.ret
String
The RET option to the MAIL command. Either FULL or HDRS.
mail.smtp.allow8bitmime
boolean
If set to true, and the server supports the 8BITMIME extension, text
parts of messages that use the "quoted-printable" or "base64" encodings
are converted to use "8bit" encoding if they follow the RFC2045 rules
for 8bit text.
mail.smtp.sendpartial
boolean
If set to true, and a message has some valid and some invalid
addresses, send the message anyway, reporting the partial failure with
a SendFailedException. If set to false (the default), the message is
not sent to any of the recipients if there is an invalid recipient
address.
mail.smtp.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.smtp.sasl.mechanisms
String
A space or comma separated list of SASL mechanism names to try
to use.
mail.smtp.sasl.authorizationid
String
The authorization ID to use in the SASL authentication.
If not set, the authentication ID (user name) is used.
mail.smtp.sasl.realm
String
The realm to use with DIGEST-MD5 authentication.
mail.smtp.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.smtp.quitwait
boolean
If set to false, the QUIT command is sent
and the connection is immediately closed.
If set to true (the default), causes the transport to wait
for the response to the QUIT command.
mail.smtp.quitonsessionreject
boolean
If set to false (the default), on session initiation rejection the QUIT
command is not sent and the connection is immediately closed.
If set to true, causes the transport to send the QUIT command prior to
closing the connection.
mail.smtp.reportsuccess
boolean
If set to true, causes the transport to include an
{@link com.sun.mail.smtp.SMTPAddressSucceededException
SMTPAddressSucceededException}
for each address that is successful.
Note also that this will cause a
{@link javax.mail.SendFailedException SendFailedException}
to be thrown from the
{@link com.sun.mail.smtp.SMTPTransport#sendMessage sendMessage}
method of
{@link com.sun.mail.smtp.SMTPTransport SMTPTransport}
even if all addresses were correct and the message was sent
successfully.
mail.smtp.socketFactory
SocketFactory
If set to a class that implements the
javax.net.SocketFactory interface, this class
will be used to create SMTP 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.smtp.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 SMTP sockets.
mail.smtp.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.smtp.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.smtp.ssl.enable
boolean
If set to true, use SSL to connect and use the SSL port by default.
Defaults to false for the "smtp" protocol and true for the "smtps" protocol.
mail.smtp.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.smtp.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.smtp.ssl.socketFactory
SSLSocketFactory
If set to a class that extends the
javax.net.ssl.SSLSocketFactory class, this class
will be used to create SMTP 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.smtp.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 SMTP SSL sockets.
mail.smtp.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.smtp.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.smtp.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.smtp.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.smtp.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.
Defaults to false.
mail.smtp.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.smtp.proxy.host
string
Specifies the host name of an HTTP web proxy server that will be used for
connections to the mail server.
mail.smtp.proxy.port
string
Specifies the port number for the HTTP web proxy server.
Defaults to port 80.
mail.smtp.proxy.user
string
Specifies the user name to use to authenticate with the HTTP web proxy server.
By default, no authentication is done.
mail.smtp.proxy.password
string
Specifies the password to use to authenticate with the HTTP web proxy server.
By default, no authentication is done.
mail.smtp.socks.host
string
Specifies the host name of a SOCKS5 proxy server that will be used for
connections to the mail server.
mail.smtp.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.smtp.mailextension
String
Extension string to append to the MAIL command.
The extension string can be used to specify standard SMTP
service extensions as well as vendor-specific extensions.
Typically the application should use the
{@link com.sun.mail.smtp.SMTPTransport SMTPTransport}
method {@link com.sun.mail.smtp.SMTPTransport#supportsExtension
supportsExtension}
to verify that the server supports the desired service extension.
See RFC 1869
and other RFCs that define specific extensions.
mail.smtp.userset
boolean
If set to true, use the RSET command instead of the NOOP command
in the {@link javax.mail.Transport#isConnected isConnected} method.
In some cases sendmail will respond slowly after many NOOP commands;
use of RSET avoids this sendmail issue.
Defaults to false.
mail.smtp.noop.strict
boolean
If set to true (the default), insist on a 250 response code from the NOOP
command to indicate success. The NOOP command is used by the
{@link javax.mail.Transport#isConnected isConnected} method to determine
if the connection is still alive.
Some older servers return the wrong response code on success, some
servers don't implement the NOOP command at all and so always return
a failure code. Set this property to false to handle servers
that are broken in this way.
Normally, when a server times out a connection, it will send a 421
response code, which the client will see as the response to the next
command it issues.
Some servers send the wrong failure response code when timing out a
connection.
Do not set this property to false when dealing with servers that are
broken in this way.
In general, applications should not need to use the classes in this
package directly. Instead, they should use the APIs defined by
javax.mail package (and subpackages). Applications should
never construct instances of SMTPTransport directly.
Instead, they should use the
Session method getTransport to acquire an
appropriate Transport object.
In addition to printing debugging output as controlled by the
{@link javax.mail.Session Session} configuration,
the com.sun.mail.smtp provider logs the same information using
{@link java.util.logging.Logger} as described in the following table:
SMTP Loggers
Logger Name
Logging Level
Purpose
com.sun.mail.smtp
CONFIG
Configuration of the SMTPTransport
com.sun.mail.smtp
FINE
General debugging output
com.sun.mail.smtp.protocol
FINEST
Complete protocol trace
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.