public class EmailTest {
    private static int hear(BufferedReader in) throws IOException {
        String line = null;
        int res = 0;

        while ((line = in.readLine()) != null) {
            String pfx = line.substring(0, 3);
            try {
                res = Integer.parseInt(pfx);
            } catch (Exception ex) {
                res = -1;
            }
            if (line.charAt(3) != '-')
                break;
        }

        return res;
    }

    private static void say(BufferedWriter wr, String text) throws IOException {
        wr.write(text + "rn");
        wr.flush();

        return;
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    private static ArrayList getMX(String hostName) throws NamingException {
        // Perform a DNS lookup for MX records in the domain
        Hashtable env = new Hashtable();
        env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
        DirContext ictx = new InitialDirContext(env);
        Attributes attrs = ictx.getAttributes(hostName, new String[] { "MX" });
        Attribute attr = attrs.get("MX");

        // if we don't have an MX record, try the machine itself
        if ((attr == null) || (attr.size() == 0)) {
            attrs = ictx.getAttributes(hostName, new String[] { "A" });
            attr = attrs.get("A");
            if (attr == null)
                throw new NamingException("No match for name '" + hostName + "'");
        }
        /*
         Huzzah! we have machines to try. Return them as an array list
         NOTE: We SHOULD take the preference into account to be absolutely
         correct. This is left as an exercise for anyone who cares.
         */
        ArrayList res = new ArrayList();
        NamingEnumeration en = attr.getAll();

        while (en.hasMore()) {
            String mailhost;
            String x = (String) en.next();
            String f[] = x.split(" ");
            // THE fix *************
            if (f.length == 1)
                mailhost = f[0];
            else if (f[1].endsWith("."))
                mailhost = f[1].substring(0, (f[1].length() - 1));
            else
                mailhost = f[1];
            // THE fix *************
            res.add(mailhost);
        }
        return res;
    }

    @SuppressWarnings("rawtypes")
    public static boolean isAddressValid(String address) {
        // Find the separator for the domain name
        int pos = address.indexOf('@');

        // If the address does not contain an '@', it's not valid
        if (pos == -1)
            return false;

        // Isolate the domain/machine name and get a list of mail exchangers
        String domain = address.substring(++pos);
        ArrayList mxList = null;
        try {
            mxList = getMX(domain);
        } catch (NamingException ex) {
            return false;
        }

        /*
        Just because we can send mail to the domain, doesn't mean that the
        address is valid, but if we can't, it's a sure sign that it isn't
        */
        if (mxList.size() == 0)
            return false;

        /*
        Now, do the SMTP validation, try each mail exchanger until we get
        a positive acceptance. It *MAY* be possible for one MX to allow
        a message [store and forwarder for example] and another [like
        the actual mail server] to reject it. This is why we REALLY ought
        to take the preference into account.
        */
        for (int mx = 0; mx < mxList.size(); mx++) {
            boolean valid = false;
            try {
                int res;
                //
                Socket skt = new Socket((String) mxList.get(mx), 25);
                BufferedReader rdr = new BufferedReader(new InputStreamReader(skt.getInputStream()));
                BufferedWriter wtr = new BufferedWriter(new OutputStreamWriter(skt.getOutputStream()));

                res = hear(rdr);
                if (res != 220)
                    throw new Exception("Invalid header");
                say(wtr, "EHLO rgagnon.com");

                res = hear(rdr);
                if (res != 250)
                    throw new Exception("Not ESMTP");

                // validate the sender address
                say(wtr, "MAIL FROM: <[email protected]>");
                res = hear(rdr);
                if (res != 250)
                    throw new Exception("Sender rejected");

                say(wtr, "RCPT TO: <" + address + ">");
                res = hear(rdr);

                // be polite
                say(wtr, "RSET");
                hear(rdr);
                say(wtr, "QUIT");
                hear(rdr);
                if (res != 250)
                    throw new Exception("Address is not valid!");

                valid = true;
                rdr.close();
                wtr.close();
                skt.close();
            } catch (Exception ex) {
                // Do nothing but try next host
                ex.printStackTrace();
            } finally {
                if (valid)
                    return true;
            }
        }
        return false;
    }

    public static void main(String args[]) {
        String testData[] = { "[email protected]", "[email protected]", "[email protected]",
        "[email protected]" };
        System.out.println(testData.length);
        for (int ctr = 0; ctr < testData.length; ctr++) {
            System.out.println(testData[ctr] + " is valid? " + isAddressValid(testData[ctr]));
        }
        return;
    }
}

public class EmailTest {
    private static int hear(BufferedReader in) throws IOException {
        String line = null;
        int res = 0;

        while ((line = in.readLine()) != null) {
            String pfx = line.substring(0, 3);
            try {
                res = Integer.parseInt(pfx);
            } catch (Exception ex) {
                res = -1;
            }
            if (line.charAt(3) != '-')
                break;
        }

        return res;
    }

    private static void say(BufferedWriter wr, String text) throws IOException {
        wr.write(text + "rn");
        wr.flush();

        return;
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    private static ArrayList getMX(String hostName) throws NamingException {
        // Perform a DNS lookup for MX records in the domain
        Hashtable env = new Hashtable();
        env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
        DirContext ictx = new InitialDirContext(env);
        Attributes attrs = ictx.getAttributes(hostName, new String[] { "MX" });
        Attribute attr = attrs.get("MX");

        // if we don't have an MX record, try the machine itself
        if ((attr == null) || (attr.size() == 0)) {
            attrs = ictx.getAttributes(hostName, new String[] { "A" });
            attr = attrs.get("A");
            if (attr == null)
                throw new NamingException("No match for name '" + hostName + "'");
        }
        /*
         Huzzah! we have machines to try. Return them as an array list
         NOTE: We SHOULD take the preference into account to be absolutely
         correct. This is left as an exercise for anyone who cares.
         */
        ArrayList res = new ArrayList();
        NamingEnumeration en = attr.getAll();

        while (en.hasMore()) {
            String mailhost;
            String x = (String) en.next();
            String f[] = x.split(" ");
            // THE fix *************
            if (f.length == 1)
                mailhost = f[0];
            else if (f[1].endsWith("."))
                mailhost = f[1].substring(0, (f[1].length() - 1));
            else
                mailhost = f[1];
            // THE fix *************
            res.add(mailhost);
        }
        return res;
    }

    @SuppressWarnings("rawtypes")
    public static boolean isAddressValid(String address) {
        // Find the separator for the domain name
        int pos = address.indexOf('@');

        // If the address does not contain an '@', it's not valid
        if (pos == -1)
            return false;

        // Isolate the domain/machine name and get a list of mail exchangers
        String domain = address.substring(++pos);
        ArrayList mxList = null;
        try {
            mxList = getMX(domain);
        } catch (NamingException ex) {
            return false;
        }

        /*
        Just because we can send mail to the domain, doesn't mean that the
        address is valid, but if we can't, it's a sure sign that it isn't
        */
        if (mxList.size() == 0)
            return false;

        /*
        Now, do the SMTP validation, try each mail exchanger until we get
        a positive acceptance. It *MAY* be possible for one MX to allow
        a message [store and forwarder for example] and another [like
        the actual mail server] to reject it. This is why we REALLY ought
        to take the preference into account.
        */
        for (int mx = 0; mx < mxList.size(); mx++) {
            boolean valid = false;
            try {
                int res;
                //
                Socket skt = new Socket((String) mxList.get(mx), 25);
                BufferedReader rdr = new BufferedReader(new InputStreamReader(skt.getInputStream()));
                BufferedWriter wtr = new BufferedWriter(new OutputStreamWriter(skt.getOutputStream()));

                res = hear(rdr);
                if (res != 220)
                    throw new Exception("Invalid header");
                say(wtr, "EHLO rgagnon.com");

                res = hear(rdr);
                if (res != 250)
                    throw new Exception("Not ESMTP");

                // validate the sender address
                say(wtr, "MAIL FROM: <[email protected]>");
                res = hear(rdr);
                if (res != 250)
                    throw new Exception("Sender rejected");

                say(wtr, "RCPT TO: <" + address + ">");
                res = hear(rdr);

                // be polite
                say(wtr, "RSET");
                hear(rdr);
                say(wtr, "QUIT");
                hear(rdr);
                if (res != 250)
                    throw new Exception("Address is not valid!");

                valid = true;
                rdr.close();
                wtr.close();
                skt.close();
            } catch (Exception ex) {
                // Do nothing but try next host
                ex.printStackTrace();
            } finally {
                if (valid)
                    return true;
            }
        }
        return false;
    }

    public static void main(String args[]) {
        String testData[] = { "[email protected]", "[email protected]", "[email protected]",
        "[email protected]" };
        System.out.println(testData.length);
        for (int ctr = 0; ctr < testData.length; ctr++) {
            System.out.println(testData[ctr] + " is valid? " + isAddressValid(testData[ctr]));
        }
        return;
    }
}

// Create a new instance of the EmailValidator class.
   EmailValidator em = new EmailValidator();
   em.MessageLogging += em_MessageLogging;
   em.EmailValidated += em_EmailValidationCompleted;
   try
   {
       string[] list = new string[3] { "[email protected]", "[email protected]", "[email protected]" };
       em.ValidateEmails(list);
   }
   catch (EmailValidatorException exc2)
   {
       Console.WriteLine("EmailValidatorException: " + exc2.Message);
   }