关于javaSMTP协议发邮件你必须知道的知识点

1.阅读官方吐槽

　　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!!!（哈哈哈笑出声）

2.抄个demo练练手

3.阅读rfc822

4.如有必要请阅读RFC 3030

• 　　SMTP协议提供程序支持RFC 3030中定义的CHUNKING扩展。
• 　　将mail.smtp.chunksize属性设置为所需的块大小（以字节为单位）。如果服务器支持CHUNKING扩展，则将使用BDAT命令以块大小发送消息。
• 　　不支持RFC 3030中描述的BINARYMIME扩展。

4.了解以下prop

　　想当初可谓是，众里寻他千百度。

　　抄代码的时候有没有想过mail.smtp.host是什么意思？虽然看名字可能知道个大概，但是这个值是从哪来的？

　　现在你知道了吗？

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.
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 setSubmitter method of 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 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.reportsuccess	boolean	If set to true, causes the transport to include an SMTPAddressSucceededException for each address that is successful. Note also that this will cause a SendFailedException to be thrown from the sendMessage method of 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 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 SMTPTransport method 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 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 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.