Smtp mail client socket problem

Question

As soon i enter the smtp server address (smtp.mail.yahoo.com) i get the following:
Exception in thread "main" java.net.UnknownHostException: smtp.mail.yahoo.com: smtp.mail.yahoo.com
        at java.net.InetAddress.getAllByName0(InetAddress.java:1128)
        at java.net.InetAddress.getAllByName0(InetAddress.java:1098)
        at java.net.InetAddress.getAllByName(InetAddress.java:1061)
        at java.net.InetAddress.getByName(InetAddress.java:958)
        at MailTest.<init>(MailTest.java:20)
        at MailTest.main(MailTest.java:97)
Java Result: 1
BUILD SUCCESSFUL (total time: 11 seconds)
import java.util.*;
import java.net.*;
import java.io.BufferedReader;
import java.io.*;
public class MailTest
    String from;
    String to;
    String smtp; //smtp.mail.yahoo.com
    String hostName;
    BufferedReader brin;
    PrintWriter pwout;
    String communication;   
    public MailTest() throws UnknownHostException,IOException
        readMailData();       
        Socket s=new Socket(InetAddress.getByName(smtp), 25);
        //tried also smtp.plus.mail.yahoo4.akadns.net and with the
        //corresponding ip
        hostName=InetAddress.getLocalHost().getHostName();
        brin=new BufferedReader(new InputStreamReader(s.getInputStream()));       
        pwout=new PrintWriter(s.getOutputStream());               
        receive();
        send("HELO "+ hostName);
        receive();
        send("MAIL FROM: <"+from+">");
        receive();
        send("DATA");
        receive();       
        send(readMessageBody());
        send(".");
        receive();
        s.close();
    private void receive() throws IOException
        System.out.println("Incoming Communication");
        System.out.println("-----------------------------------------");
        while (!(communication=brin.readLine()).equals(null))
            System.out.println(communication);
        System.out.println("-----------------------------------------");
    private void send(String s) throws IOException
        System.out.println("Outcoming Communication");
        System.out.println(s);
        pwout.write(s);
        pwout.flush();
        System.out.println("-----------------------------------------");
    private String readMessageBody() throws IOException
        String q="";
        String msgBuffer="";
        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
        System.out.println("--------------Message--Body--------------");
        System.out.println("enter -Enter-quit-Enter- to exit");
        System.out.print(">");       
        q=in.readLine();       
        while (!q.equals("quit"));
            msgBuffer+=q;
            System.out.print(">");
            q=in.readLine();           
        System.out.println("-----------------------------------------");
        return msgBuffer;
    private void readMailData() throws IOException
        BufferedReader in= new BufferedReader(new InputStreamReader(System.in));                       
        System.out.println("From: ");
        from=in.readLine().trim();
        System.out.println("To: ");
        to=in.readLine().trim();
        System.out.println("SMTP server: ");
        smtp=in.readLine();       
    public static void main(String[] args) throws UnknownHostException, IOException           
        MailTest mt=new MailTest();
}

Answer 1

I would say you have a DNS problem, or perhaps you aren't connected to the Internet. Can you ping smtp.mail.yahoo.com? or at least can ping resolve the name?