尽管这个问题已经结束，我想发布一个计数器解决方案，但现在使用简单Java邮件(开源JavaMail smtp包装器):

final Email email = new Email();

String host = "smtp.gmail.com";
Integer port = 587;
String from = "username";
String pass = "password";
String[] to = {"to@gmail.com"};

email.setFromAddress("", from);
email.setSubject("sending in a group");
for( int i=0; i < to.length; i++ ) {
    email.addRecipient("", to[i], RecipientType.TO);
}
email.setText("Welcome to JavaMail");

new Mailer(host, port, from, pass).sendMail(email);
// you could also still use your mail session instead
new Mailer(session).sendMail(email);

//set CLASSPATH=%CLASSPATH%;activation.jar;mail.jar
import javax.mail.*;
import javax.mail.internet.*;
import java.util.*;

public class Mail
{
    String  d_email = "iamdvr@gmail.com",
            d_password = "****",
            d_host = "smtp.gmail.com",
            d_port  = "465",
            m_to = "iamdvr@yahoo.com",
            m_subject = "Testing",
            m_text = "Hey, this is the testing email using smtp.gmail.com.";
    public static void main(String[] args)
    {
        String[] to={"XXX@yahoo.com"};
        String[] cc={"XXX@yahoo.com"};
        String[] bcc={"XXX@yahoo.com"};
        //This is for google
        Mail.sendMail("venkatesh@dfdf.com", "password", "smtp.gmail.com", 
                      "465", "true", "true", 
                      true, "javax.net.ssl.SSLSocketFactory", "false", 
                      to, cc, bcc, 
                      "hi baba don't send virus mails..", 
                      "This is my style...of reply..If u send virus mails..");
    }

    public synchronized static boolean sendMail(
        String userName, String passWord, String host, 
        String port, String starttls, String auth, 
        boolean debug, String socketFactoryClass, String fallback, 
        String[] to, String[] cc, String[] bcc, 
        String subject, String text) 
    {
        Properties props = new Properties();
        //Properties props=System.getProperties();
        props.put("mail.smtp.user", userName);
        props.put("mail.smtp.host", host);
        if(!"".equals(port))
            props.put("mail.smtp.port", port);
        if(!"".equals(starttls))
            props.put("mail.smtp.starttls.enable",starttls);
        props.put("mail.smtp.auth", auth);
        if(debug) {
            props.put("mail.smtp.debug", "true");
        } else {
            props.put("mail.smtp.debug", "false");         
        }
        if(!"".equals(port))
            props.put("mail.smtp.socketFactory.port", port);
        if(!"".equals(socketFactoryClass))
            props.put("mail.smtp.socketFactory.class",socketFactoryClass);
        if(!"".equals(fallback))
            props.put("mail.smtp.socketFactory.fallback", fallback);

        try
        {
            Session session = Session.getDefaultInstance(props, null);
            session.setDebug(debug);
            MimeMessage msg = new MimeMessage(session);
            msg.setText(text);
            msg.setSubject(subject);
            msg.setFrom(new InternetAddress("p_sambasivarao@sutyam.com"));
            for(int i=0;i<to.length;i++) {
                msg.addRecipient(Message.RecipientType.TO, 
                                 new InternetAddress(to[i]));
            }
            for(int i=0;i<cc.length;i++) {
                msg.addRecipient(Message.RecipientType.CC, 
                                 new InternetAddress(cc[i]));
            }
            for(int i=0;i<bcc.length;i++) {
                msg.addRecipient(Message.RecipientType.BCC, 
                                 new InternetAddress(bcc[i]));
            }
            msg.saveChanges();
            Transport transport = session.getTransport("smtp");
            transport.connect(host, userName, passWord);
            transport.sendMessage(msg, msg.getAllRecipients());
            transport.close();
            return true;
        }
        catch (Exception mex)
        {
            mex.printStackTrace();
            return false;
        }
    }

}

增值:

主题、消息和显示名称中的编码缺陷 现代Java邮件库版本只需要一个神奇的属性 建议Session.getInstance()优于Session.getDefaultInstance() 附件 谷歌关闭不太安全的应用程序后仍然有效:在您的组织中启用2因素身份验证->打开2FA ->生成应用程序密码。

    import java.io.File;
    import java.nio.charset.StandardCharsets;
    import java.util.Properties;
    import java.util.logging.Level;
    import java.util.logging.Logger;
    import javax.activation.DataHandler;
    import javax.mail.Message;
    import javax.mail.Session;
    import javax.mail.Transport;
    import javax.mail.internet.InternetAddress;
    import javax.mail.internet.MimeBodyPart;
    import javax.mail.internet.MimeMessage;
    import javax.mail.internet.MimeMultipart;
    import javax.mail.util.ByteArrayDataSource;
    
    public class Gmailer {
      private static final Logger LOGGER = Logger.getLogger(Gmailer.class.getName());
    
      public static void main(String[] args) {
        send();
      }
    
      public static void send() {
        Transport transport = null;
        try {
          String accountEmail = "account@source.com";
          String accountAppPassword = "";
          String displayName = "Display-Name 東";
          String replyTo = "reply-to@source.com";
    
          String to = "to@target.com";
          String cc = "cc@target.com";
          String bcc = "bcc@target.com";
    
          String subject = "Subject 東";
          String message = "<span style='color: red;'>東</span>";
          String type = "html"; // or "plain"
          String mimeTypeWithEncoding = "text/" + type + "; charset=" + StandardCharsets.UTF_8.name();
    
          File attachmentFile = new File("Attachment.pdf");
          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types
          String attachmentMimeType = "application/pdf";
          byte[] bytes = ...; // read file to byte array
    
          Properties properties = System.getProperties();
          properties.put("mail.debug", "true");
          // i found that this is the only property necessary for a modern java mail version
          properties.put("mail.smtp.starttls.enable", "true");
          // https://javaee.github.io/javamail/FAQ#getdefaultinstance
          Session session = Session.getInstance(properties);
    
          MimeMessage mimeMessage = new MimeMessage(session);
    
          // probably best to use the account email address, to avoid landing in spam or blacklists
          // not even sure if the server would accept a differing from address
          InternetAddress from = new InternetAddress(accountEmail);
          from.setPersonal(displayName, StandardCharsets.UTF_8.name());
          mimeMessage.setFrom(from);
    
          mimeMessage.setReplyTo(InternetAddress.parse(replyTo));
    
          mimeMessage.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
          mimeMessage.setRecipients(Message.RecipientType.CC, InternetAddress.parse(cc));
          mimeMessage.setRecipients(Message.RecipientType.BCC, InternetAddress.parse(bcc));
    
          mimeMessage.setSubject(subject, StandardCharsets.UTF_8.name());
    
          MimeMultipart multipart = new MimeMultipart();
    
          MimeBodyPart messagePart = new MimeBodyPart();
          messagePart.setContent(mimeMessage, mimeTypeWithEncoding);
          multipart.addBodyPart(messagePart);
    
          MimeBodyPart attachmentPart = new MimeBodyPart();
          attachmentPart.setDataHandler(new DataHandler(new ByteArrayDataSource(bytes, attachmentMimeType)));
          attachmentPart.setFileName(attachmentFile.getName());
          multipart.addBodyPart(attachmentPart);
    
          mimeMessage.setContent(multipart);
    
          transport = session.getTransport();
          transport.connect("smtp.gmail.com", 587, accountEmail, accountAppPassword);
          transport.sendMessage(mimeMessage, mimeMessage.getAllRecipients());
        }
        catch(Exception e) {
          // I prefer to bubble up exceptions, so the caller has the info that someting went wrong, and gets a chance to handle it.
          // I also prefer not to force the exception in the signature.
          throw e instanceof RuntimeException ? (RuntimeException) e : new RuntimeException(e);
        }
        finally {
          if(transport != null) {
            try {
              transport.close();
            }
            catch(Exception e) {
              LOGGER.log(Level.WARNING, "failed to close java mail transport: " + e);
            }
          }
        }
      }
    }

就像这样(听起来你只需要改变你的SMTP服务器):

String host = "smtp.gmail.com";
String from = "user name";
Properties props = System.getProperties();
props.put("mail.smtp.host", host);
props.put("mail.smtp.user", from);
props.put("mail.smtp.password", "asdfgh");
props.put("mail.smtp.port", "587"); // 587 is the port number of yahoo mail
props.put("mail.smtp.auth", "true");

Session session = Session.getDefaultInstance(props, null);
MimeMessage message = new MimeMessage(session);
message.setFrom(new InternetAddress(from));

InternetAddress[] to_address = new InternetAddress[to.length];
int i = 0;
// To get the array of addresses
while (to[i] != null) {
    to_address[i] = new InternetAddress(to[i]);
    i++;
}
System.out.println(Message.RecipientType.TO);
i = 0;
while (to_address[i] != null) {

    message.addRecipient(Message.RecipientType.TO, to_address[i]);
    i++;
}
message.setSubject("sending in a group");
message.setText("Welcome to JavaMail");
// alternately, to send HTML mail:
// message.setContent("<p>Welcome to JavaMail</p>", "text/html");
Transport transport = session.getTransport("smtp");
transport.connect("smtp.mail.yahoo.co.in", "user name", "asdfgh");
transport.sendMessage(message, message.getAllRecipients());
transport.close();

如果你想使用outlook和Javamail API，那么使用

smtp-mail.outlook.com

更多和完整的工作代码检查这个答案。

最低要求:

import java.util.Properties;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class MessageSender {

    public static void sendHardCoded() throws AddressException, MessagingException {
        String to = "a@a.info";
        final String from = "b@gmail.com";

        Properties properties = new Properties();
        properties.put("mail.smtp.starttls.enable", "true");
        properties.put("mail.smtp.auth", "true");
        properties.put("mail.smtp.host", "smtp.gmail.com");
        properties.put("mail.smtp.port", "587");

        Session session = Session.getInstance(properties,
                new javax.mail.Authenticator() {
                    protected PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication(from, "BeNice");
                    }
                });

        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
        message.setSubject("Hello");
        message.setText("What's up?");

        Transport.send(message);
    }

}