Question

我正在为支票yahoo帐户编写此代码，但无法响应yahoo？我需要像本网站（verifyemailaddress.io）这样的写服务验证电子邮件地址是否真实的最佳方法是验证是否有注册到域名的邮件服务器。使用代码时，我注意到灰名单存在问题。灰名单是一种反垃圾邮件尝试，它首次拒绝三重客户端，发送者和地址到达SMTP服务器的服务。灰名单会发回暂时错误（450），因此该地址为否认。在这种情况下，最好接受地址经过验证，因为没有更好的信息那时可用。导入java.io. ; 导入java.net。; 导入java.util。; 导入javax.naming。；导入javax.naming.directory。*;

public class SMTP {
    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 + "\r\n" );
    wr.flush();

    return;
    }

    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 x = (String) en.next();
        String f[] = x.split( " " );
        if ( f[1].endsWith( "." ) ) 
            f[1] = f[1].substring( 0, (f[1].length() - 1));
        res.add( f[1] );
    }
    return res;
    }

    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 orbaker.com" );

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

            // validate the sender address  
            say( wtr, "MAIL FROM: <tim@orbaker.com>" );
            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
        } 
        finally {
            if ( valid ) return true;
        }
    }
    return false;
    }

    public static void main( String args[] ) {
    String testData[] = {
        "tim@orbaker.com", // Valid address
        "fail.me@nowhere.spam", // Invalid domain name
        "arkham@bigmeanogre.net", // Invalid address
        "nosuchaddress@yahoo.com" // Failure of this method
        };

    for ( int ctr = 0 ; ctr < testData.length ; ctr++ ) {
        System.out.println( testData[ ctr ] + " is valid? " + 
            isAddressValid( testData[ ctr ] ) );
    }
    return;
    }
}

如何检查Yahoo帐户可以指导我？

如何实用地检查yahoo电子邮件是否存在？

0 个答案: