一个简单的方法是为POP3访问配置/启用gmail帐户。这将允许您通过gmail服务器通过普通SMTP发送邮件。

然后通过smtp.gmail.com发送(端口587)

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);
            }
          }
        }
      }
    }

这就是我所做的，当我想发送带有附件的电子邮件时，工作正常。：）

 public class NewClass {

    public static void main(String[] args) {
        try {
            Properties props = System.getProperties();
            props.put("mail.smtp.starttls.enable", "true");
            props.put("mail.smtp.host", "smtp.gmail.com");
            props.put("mail.smtp.auth", "true");
            props.put("mail.smtp.port", "465"); // smtp port
            Authenticator auth = new Authenticator() {

                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication("username-gmail", "password-gmail");
                }
            };
            Session session = Session.getDefaultInstance(props, auth);
            MimeMessage msg = new MimeMessage(session);
            msg.setFrom(new InternetAddress("username-gmail@gmail.com"));
            msg.setSubject("Try attachment gmail");
            msg.setRecipient(RecipientType.TO, new InternetAddress("username-gmail@gmail.com"));
            //add atleast simple body
            MimeBodyPart body = new MimeBodyPart();
            body.setText("Try attachment");
            //do attachment
            MimeBodyPart attachMent = new MimeBodyPart();
            FileDataSource dataSource = new FileDataSource(new File("file-sent.txt"));
            attachMent.setDataHandler(new DataHandler(dataSource));
            attachMent.setFileName("file-sent.txt");
            attachMent.setDisposition(MimeBodyPart.ATTACHMENT);
            Multipart multipart = new MimeMultipart();
            multipart.addBodyPart(body);
            multipart.addBodyPart(attachMent);
            msg.setContent(multipart);
            Transport.send(msg);
        } catch (AddressException ex) {
            Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
        } catch (MessagingException ex) {
            Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

这是一个使用Gmail发送电子邮件的简单类。您需要将JavaMail库添加到构建路径中，或者直接使用Maven。

import java.util.Properties;

import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;

public class GmailSender
{
    private static String protocol = "smtp";

    private String username;
    private String password;

    private Session session;
    private Message message;
    private Multipart multipart;

    public GmailSender()
    {
        this.multipart = new MimeMultipart();
    }

    public void setSender(String username, String password)
    {
        this.username = username;
        this.password = password;

        this.session = getSession();
        this.message = new MimeMessage(session);
    }

    public void addRecipient(String recipient) throws AddressException, MessagingException
    {
        message.addRecipient(Message.RecipientType.TO, new InternetAddress(recipient));
    }

    public void setSubject(String subject) throws MessagingException
    {
        message.setSubject(subject);
    }

    public void setBody(String body) throws MessagingException
    {
        BodyPart messageBodyPart = new MimeBodyPart();
        messageBodyPart.setText(body);
        multipart.addBodyPart(messageBodyPart);

        message.setContent(multipart);
    }

    public void send() throws MessagingException
    {
        Transport transport = session.getTransport(protocol);
        transport.connect(username, password);
        transport.sendMessage(message, message.getAllRecipients());

        transport.close();
    }

    public void addAttachment(String filePath) throws MessagingException
    {
        BodyPart messageBodyPart = getFileBodyPart(filePath);
        multipart.addBodyPart(messageBodyPart);

        message.setContent(multipart);
    }

    private BodyPart getFileBodyPart(String filePath) throws MessagingException
    {
        BodyPart messageBodyPart = new MimeBodyPart();
        DataSource dataSource = new FileDataSource(filePath);
        messageBodyPart.setDataHandler(new DataHandler(dataSource));
        messageBodyPart.setFileName(filePath);

        return messageBodyPart;
    }

    private Session getSession()
    {
        Properties properties = getMailServerProperties();
        Session session = Session.getDefaultInstance(properties);

        return session;
    }

    private Properties getMailServerProperties()
    {
        Properties properties = System.getProperties();
        properties.put("mail.smtp.starttls.enable", "true");
        properties.put("mail.smtp.host", protocol + ".gmail.com");
        properties.put("mail.smtp.user", username);
        properties.put("mail.smtp.password", password);
        properties.put("mail.smtp.port", "587");
        properties.put("mail.smtp.auth", "true");

        return properties;
    }
}

使用示例:

GmailSender sender = new GmailSender();
sender.setSender("myEmailNameWithout@gmail.com", "mypassword");
sender.addRecipient("recipient@somehost.com");
sender.setSubject("The subject");
sender.setBody("The body");
sender.addAttachment("TestFile.txt");
sender.send();

我的完整代码如下所示，运行良好:

package ripon.java.mail;
import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;

public class SendEmail
{
public static void main(String [] args)
{    
    // Sender's email ID needs to be mentioned
     String from = "test@gmail.com";
     String pass ="test123";
    // Recipient's email ID needs to be mentioned.
   String to = "ripon420@yahoo.com";

   String host = "smtp.gmail.com";

   // Get system properties
   Properties properties = System.getProperties();
   // Setup mail server
   properties.put("mail.smtp.starttls.enable", "true");
   properties.put("mail.smtp.host", host);
   properties.put("mail.smtp.user", from);
   properties.put("mail.smtp.password", pass);
   properties.put("mail.smtp.port", "587");
   properties.put("mail.smtp.auth", "true");

   // Get the default Session object.
   Session session = Session.getDefaultInstance(properties);

   try{
      // Create a default MimeMessage object.
      MimeMessage message = new MimeMessage(session);

      // Set From: header field of the header.
      message.setFrom(new InternetAddress(from));

      // Set To: header field of the header.
      message.addRecipient(Message.RecipientType.TO,
                               new InternetAddress(to));

      // Set Subject: header field
      message.setSubject("This is the Subject Line!");

      // Now set the actual message
      message.setText("This is actual message");

      // Send message
      Transport transport = session.getTransport("smtp");
      transport.connect(host, from, pass);
      transport.sendMessage(message, message.getAllRecipients());
      transport.close();
      System.out.println("Sent message successfully....");
   }catch (MessagingException mex) {
      mex.printStackTrace();
   }
}
}

一个简单的方法是为POP3访问配置/启用gmail帐户。这将允许您通过gmail服务器通过普通SMTP发送邮件。

然后通过smtp.gmail.com发送(端口587)