javamail电子邮件不发送

Posted 2023-03-14

【中文标题】javamail电子邮件不发送

【英文标题】：javamail email not send

【发布时间】：2012-04-27 10:30:36

【问题描述】：

我正在尝试使用 javamail 发送电子邮件，但我是这个主题的新手。到目前为止，我没有收到编译错误或运行错误，但电子邮件从未发送。我使用一个帮助类来发送带有本地 SMTP 服务器（MailUtilLocal.java）和发送电子邮件的 servlet（EmailServlet）的电子邮件。代码如下：

` //EmailServlet.java:

import Beans.Usuario;
import IOBD.InputOutputBD;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.mail.MessagingException;
import Servlets.MailUtilLocal;
import java.util.*;

public class EmailServlet extends HttpServlet 

protected void doPost(HttpServletRequest request,
        HttpServletResponse response)
        throws ServletException, IOException 
    // get parameters from the request
    String userId = request.getParameter("userId");
    String password = request.getParameter("password");
    String nombre = request.getParameter("nombre");
    String tipo = request.getParameter("tipo");
    String emailAddress = request.getParameter("emailAddress");
 // create the User object and write it to a file
    Usuario user = new Usuario(userId, password, nombre, tipo, emailAddress);
    ServletContext sc = getServletContext();

 // store the User object in the session
    HttpSession session = request.getSession();
    session.setAttribute("user", user);


 // send email to user
    String to = emailAddress;
    String from = "[e-mail]";
    String subject = "Welcome to our email list";
    String body = "Dear " + nombre + ",\n\n"
            + "Thanks for joining our email list. "
            + "We'll make sure to send you announcements "
            + "about new products and promotions.\n"
            + "Have a great day and thanks again!\n\n"
            + "Kelly Slivkoff\n" + "Mike Murach & Associates";
    boolean isBodyhtml = false;
    try 
        MailUtilLocal.sendMail(to, from, subject, body, isBodyHTML);
     catch (MessagingException e) 
        String errorMessage =
                "ERROR: Unable to send email. "
                + "Check Tomcat logs for details.<br>"
                + "NOTE: You may need to configure your "
                + "system as described in chapter 15.<br>"
                + "ERROR MESSAGE: " + e.getMessage();
        request.setAttribute("errorMessage", errorMessage);
        this.log("Unable to send email. \n"
                + "Here is the email you tried to send: \n"
                + "=====================================\n"
                + "TO: " + emailAddress + "\n"
                + "FROM: " + from + "\n"
                + "SUBJECT: " + subject + "\n"
                + "\n"
                + body + "\n\n");


    
    // forward request and response to JSP page
    String url = "/index.jsp";
    RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(url);
    dispatcher.forward(request, response);

//MailUtilLocal.java:

import java.util.Properties;
import javax.mail.*;
import javax.mail.internet.*;

public class MailUtilLocal 

public static void sendMail(String to, String from, String subject, String body,   boolean bodyIsHTML)
        throws MessagingException 
    // 1 - get a mail session
    Properties props = new Properties();
    props.put("mail.transport.protocol", "smtp");
    props.put("mail.smtp.host", "localhost");
    props.put("mail.smtp.port", 25);
    Session session = Session.getDefaultInstance(props);
    session.setDebug(true);
    // 2 - create a message
    Message message = new MimeMessage(session);
    message.setSubject(subject);
    if (bodyIsHTML) 
        message.setContent(body, "text/html");
     else 
        message.setText(body);
    
    // 3 - address the message
    Address fromAddress = new InternetAddress(from);
    Address toAddress = new InternetAddress(to);
    message.setFrom(fromAddress);
    message.setRecipient(Message.RecipientType.TO, toAddress);
    // 4 - send the message
    Transport.send(message);

我删除了这两行，因为在 UserIO 上没有方法 addRecord 时出现错误，并且我不知道其中应该包含什么

String path = sc.getRealPath("/WEB-INF/EmailList.txt");
UserIO.addRecord(user, path);

【问题讨论】：

您应该使用像 common email 或 spring email 这样的帮助库，而不是编写样板代码。其次，你没有捕捉到所有的异常，可能有一个没有被注意到。

为什么在这行代码props.put("mail.smtp.host", "localhost");中指定localhost。您需要在此处指定特定的邮件服务器。

@Lion OP 提到它是一个本地邮件服务器。

哦，读到这我都困了！

JavaMail FAQ 有一些调试技巧。

【参考方案1】：

当您使用本地 smtp 服务器时，有时会发生的情况是您的 ISP 会阻止端口 25，因此您的 SMTP 服务器无法与远程服务器通信。

在这种情况下，您可以使用不同的端口从您的 smtp 服务器发送电子邮件，或使用接受来自 25 以外的端口（通常是 587 和 465）的连接的第三方服务。

看看Sendgrid、mailjet和postmarkapp，因为它们是一些最知名的提供商