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## org.apache.commons.net.smtp
Class SMTPClient

    java.lang.Object
      org.apache.commons.net.SocketClient
          org.apache.commons.net.smtp.SMTP
              org.apache.commons.net.smtp.SMTPClient

Direct Known Subclasses:
  SMTPSClient

    public class SMTPClient

extends SMTP

SMTPClient encapsulates all the functionality necessary to send files through an SMTP server. This class takes care of all low level details of interacting with an SMTP server and provides a convenient higher level interface. As with all classes derived from `SocketClient`, you must first connect to the server with `connect` before doing anything, and finally `disconnect` after you're completely finished interacting with the server. Then you need to check the SMTP reply code to see if the connection was successful. For example:

        try {
          int reply;
          client.connect("mail.foobar.com");
          System.out.print(client.getReplyString());

          // After connection attempt, you should check the reply code to verify
          // success.
          reply = client.getReplyCode();

          if(!SMTPReply.isPositiveCompletion(reply)) {
            client.disconnect();
            System.err.println("SMTP server refused connection.");
            System.exit(1);
          }

          // Do useful stuff here.
          ...
        } catch(IOException e) {
          if(client.isConnected()) {
            try {
              client.disconnect();
            } catch(IOException f) {
              // do nothing
            }
          }
          System.err.println("Could not connect to server.");
          e.printStackTrace();
          System.exit(1);
        }

Immediately after connecting is the only real time you need to check the reply code (because connect is of type void). The convention for all the SMTP command methods in SMTPClient is such that they either return a boolean value or some other value. The boolean methods return true on a successful completion reply from the SMTP server and false on a reply resulting in an error condition or failure. The methods returning a value other than boolean return a value containing the higher level data produced by the SMTP command, or null if a reply resulted in an error condition or failure. If you want to access the exact SMTP reply code causing a success or failure, you must call `getReplyCode` after a success or failure.

You should keep in mind that the SMTP server may choose to prematurely close a connection for various reasons. The SMTPClient class will detect a premature SMTP server connection closing when it receives a `SMTPReply.SERVICE_NOT_AVAILABLE` response to a command. When that occurs, the method encountering that reply will throw an `SMTPConnectionClosedException` . `SMTPConectionClosedException` is a subclass of `IOException` and therefore need not be caught separately, but if you are going to catch it separately, its catch block must appear before the more general `IOException` catch block. When you encounter an `SMTPConnectionClosedException` , you must disconnect the connection with `disconnect()` to properly clean up the system resources used by SMTPClient. Before disconnecting, you may check the last reply code and text with `getReplyCode` , `getReplyString` , and `getReplyStrings`.

Rather than list it separately for each method, we mention here that every method communicating with the server and throwing an IOException can also throw a `MalformedServerReplyException` , which is a subclass of IOException. A MalformedServerReplyException will be thrown when the reply received from the server deviates enough from the protocol specification that it cannot be interpreted in a useful manner despite attempts to be as lenient as possible.

See Also:
  `SMTP`, `SimpleSMTPHeader`, `RelayPath`, `SMTPConnectionClosedException`, `MalformedServerReplyException`

Field Summary

Fields inherited from class org.apache.commons.net.smtp.SMTP
`_commandSupport_, DEFAULT_PORT, encoding`

Fields inherited from class org.apache.commons.net.SocketClient
`_defaultPort_, _input_, _output_, _serverSocketFactory_, _socket_, _socketFactory_, _timeout_, connectTimeout, NETASCII_EOL`

Constructor Summary
`SMTPClient()` Default SMTPClient constructor.
`SMTPClient(String encoding)` Overloaded constructor that takes an encoding specification

Method Summary
`boolean` | `addRecipient(RelayPath path)` Add a recipient for a message using the SMTP RCPT command, specifying a forward relay path.
`boolean` | `addRecipient(String address)` Add a recipient for a message using the SMTP RCPT command, the recipient's email address.
`boolean` | `completePendingCommand()` At least one SMTPClient method (`sendMessageData` ) does not complete the entire sequence of SMTP commands to complete a transaction.
`String` | `listHelp()` Fetches the system help information from the server and returns the full string.
`String` | `listHelp(String command)` Fetches the help information for a given command from the server and returns the full string.
`boolean` | `login()` Login to the SMTP server by sending the HELO command with the client hostname as an argument.
`boolean` | `login(String hostname)` Login to the SMTP server by sending the HELO command with the given hostname as an argument.
`boolean` | `logout()` Logout of the SMTP server by sending the QUIT command.
`boolean` | `reset()` Aborts the current mail transaction, resetting all server stored sender, recipient, and mail data, cleaing all buffers and tables.
`Writer` | `sendMessageData()` Send the SMTP DATA command in preparation to send an email message.
`boolean` | `sendNoOp()` Sends a NOOP command to the SMTP server.
`boolean` | `sendShortMessageData(String message)` A convenience method for sending short messages.
`boolean` | `sendSimpleMessage(String sender, String[] recipients, String message)` A convenience method for a sending short email without having to explicitly set the sender and recipient(s).
`boolean` | `sendSimpleMessage(String sender, String recipient, String message)` A convenience method for a sending short email without having to explicitly set the sender and recipient(s).
`boolean` | `setSender(RelayPath path)` Set the sender of a message using the SMTP MAIL command, specifying a reverse relay path.
`boolean` | `setSender(String address)` Set the sender of a message using the SMTP MAIL command, specifying the sender's email address.
`boolean` | `verify(String username)` Verify that a username or email address is valid, i.e., that mail can be delivered to that mailbox on the server.

Methods inherited from class org.apache.commons.net.smtp.SMTP
`_connectAction_, data, disconnect, expn, getCommandSupport, getReply, getReplyCode, getReplyString, getReplyStrings, helo, help, help, mail, noop, quit, rcpt, removeProtocolCommandistener, rset, saml, send, sendCommand, sendCommand, sendCommand, sendCommand, soml, turn, vrfy`

Methods inherited from class org.apache.commons.net.SocketClient
`addProtocolCommandListener, connect, connect, connect, connect, connect, connect, createCommandSupport, fireCommandSent, fireReplyReceived, getConnectTimeout, getDefaultPort, getDefaultTimeout, getKeepAlive, getLocalAddress, getLocalPort, getReceiveBufferSize, getRemoteAddress, getRemotePort, getSendBufferSize, getServerSocketFactory, getSoLinger, getSoTimeout, getTcpNoDelay, isAvailable, isConnected, removeProtocolCommandListener, setConnectTimeout, setDefaultPort, setDefaultTimeout, setKeepAlive, setReceiveBufferSize, setSendBufferSize, setServerSocketFactory, setSocketFactory, setSoLinger, setSoTimeout, setTcpNoDelay, verifyRemote`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### SMTPClient

    public SMTPClient()

  Default SMTPClient constructor. Creates a new SMTPClient instance.

### SMTPClient

    public SMTPClient(String encoding)

  Overloaded constructor that takes an encoding specification

  Parameters:
    `encoding` - The encoding to use
  Since:
    2.0

Method Detail

### completePendingCommand

    public boolean completePendingCommand()
                                   throws IOException

  At least one SMTPClient method (`sendMessageData` ) does not complete the entire sequence of SMTP commands to complete a transaction. These types of commands require some action by the programmer after the reception of a positive intermediate command. After the programmer's code completes its actions, it must call this method to receive the completion reply from the server and verify the success of the entire transaction.

  For example,

       writer = client.sendMessage();
       if(writer == null) // failure
         return false;
       header =
        new SimpleSMTPHeader("foobar@foo.com", "foo@foobar.com", "Re: Foo");
       writer.write(header.toString());
       writer.write("This is just a test");
       writer.close();
       if(!client.completePendingCommand()) // failure
         return false;

  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### login

    public boolean login(String hostname)
                  throws IOException

  Login to the SMTP server by sending the HELO command with the given hostname as an argument. Before performing any mail commands, you must first login.

  Parameters:
    `hostname` - The hostname with which to greet the SMTP server.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### login

    public boolean login()
                  throws IOException

  Login to the SMTP server by sending the HELO command with the client hostname as an argument. Before performing any mail commands, you must first login.

  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### setSender

    public boolean setSender(RelayPath path)
                      throws IOException

  Set the sender of a message using the SMTP MAIL command, specifying a reverse relay path. The sender must be set first before any recipients may be specified, otherwise the mail server will reject your commands.

  Parameters:
    `path` - The reverse relay path pointing back to the sender.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### setSender

    public boolean setSender(String address)
                      throws IOException

  Set the sender of a message using the SMTP MAIL command, specifying the sender's email address. The sender must be set first before any recipients may be specified, otherwise the mail server will reject your commands.

  Parameters:
    `address` - The sender's email address.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### addRecipient

    public boolean addRecipient(RelayPath path)
                         throws IOException

  Add a recipient for a message using the SMTP RCPT command, specifying a forward relay path. The sender must be set first before any recipients may be specified, otherwise the mail server will reject your commands.

  Parameters:
    `path` - The forward relay path pointing to the recipient.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### addRecipient

    public boolean addRecipient(String address)
                         throws IOException

  Add a recipient for a message using the SMTP RCPT command, the recipient's email address. The sender must be set first before any recipients may be specified, otherwise the mail server will reject your commands.

  Parameters:
    `address` - The recipient's email address.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### sendMessageData

    public Writer sendMessageData()
                           throws IOException

  Send the SMTP DATA command in preparation to send an email message. This method returns a DotTerminatedMessageWriter instance to which the message can be written. Null is returned if the DATA command fails.

  You must not issue any commands to the SMTP server (i.e., call any (other methods) until you finish writing to the returned Writer instance and close it. The SMTP protocol uses the same stream for issuing commands as it does for returning results. Therefore the returned Writer actually writes directly to the SMTP connection. After you close the writer, you can execute new commands. If you do not follow these requirements your program will not work properly.

  You can use the provided `SimpleSMTPHeader` class to construct a bare minimum header. To construct more complicated headers you should refer to RFC 822. When the Java Mail API is finalized, you will be able to use it to compose fully compliant Internet text messages. The DotTerminatedMessageWriter takes care of doubling line-leading dots and ending the message with a single dot upon closing, so all you have to worry about is writing the header and the message.

  Upon closing the returned Writer, you need to call `completePendingCommand()` to finalize the transaction and verify its success or failure from the server reply.

  Returns:
    A DotTerminatedMessageWriter to which the message (including header) can be written. Returns null if the command fails.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### sendShortMessageData

    public boolean sendShortMessageData(String message)
                                 throws IOException

  A convenience method for sending short messages. This method fetches the Writer returned by `sendMessageData()` and writes the specified String to it. After writing the message, this method calls `completePendingCommand()` to finalize the transaction and returns its success or failure.

  Parameters:
    `message` - The short email message to send.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### sendSimpleMessage

    public boolean sendSimpleMessage(String sender,
                                     String recipient,
                                     String message)
                              throws IOException

  A convenience method for a sending short email without having to explicitly set the sender and recipient(s). This method sets the sender and recipient using `setSender` and `addRecipient` , and then sends the message using `sendShortMessageData` .

  Parameters:
    `sender` - The email address of the sender.
    `recipient` - The email address of the recipient.
    `message` - The short email message to send.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### sendSimpleMessage

    public boolean sendSimpleMessage(String sender,
                                     String[] recipients,
                                     String message)
                              throws IOException

  A convenience method for a sending short email without having to explicitly set the sender and recipient(s). This method sets the sender and recipients using `setSender` and `addRecipient` , and then sends the message using `sendShortMessageData` .

  Parameters:
    `sender` - The email address of the sender.
    `recipients` - An array of recipient email addresses.
    `message` - The short email message to send.
  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### logout

    public boolean logout()
                   throws IOException

  Logout of the SMTP server by sending the QUIT command.

  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### reset

    public boolean reset()
                  throws IOException

  Aborts the current mail transaction, resetting all server stored sender, recipient, and mail data, cleaing all buffers and tables.

  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### verify

    public boolean verify(String username)
                   throws IOException

  Verify that a username or email address is valid, i.e., that mail can be delivered to that mailbox on the server.

  Parameters:
    `username` - The username or email address to validate.
  Returns:
    True if the username is valid, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### listHelp

    public String listHelp()
                    throws IOException

  Fetches the system help information from the server and returns the full string.

  Returns:
    The system help string obtained from the server. null if the information could not be obtained.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### listHelp

    public String listHelp(String command)
                    throws IOException

  Fetches the help information for a given command from the server and returns the full string.

  Parameters:
    `command` - The command on which to ask for help.
  Returns:
    The command help string obtained from the server. null if the information could not be obtained.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

### sendNoOp

    public boolean sendNoOp()
                     throws IOException

  Sends a NOOP command to the SMTP server. This is useful for preventing server timeouts.

  Returns:
    True if successfully completed, false if not.
  Throws:
    `SMTPConnectionClosedException` - If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or independently as itself.
    `IOException` - If an I/O error occurs while either sending a command to the server or receiving a reply from the server.

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