java - 如何解决: Sending the email to the following server failed SocketException: Permission denied: connect

Question

我在使用 Java 以编程方式发送邮件时遇到问题。我从网络团队确认，使用防火墙通过 Java 发送邮件被阻止。但我能够在 Windows 命令提示符中从 telnet 获取响应。请在下面找到详细信息。

用于使用 Javax Mail 发送邮件的代码:

public static void main(String[] args) throws MessagingException {
        String host = "mailhost.xxx";
        String to = "abc@xyz.edu";
        String from = "cde@xyz.edu";
        String subject = "test";
        String messageText = "body test";

        Properties props = System.getProperties();
        props.put("mail.host", host);
        props.put("mail.transport.protocol", "smtp");
        props.put("mail.smtp.port", "25");

        // If using authentication, otherwise comment out
        props.put("mail.smtp.auth", "true");

        // Gmail requires TLS, your server may not
        props.put("mail.smtp.starttls.enable", "true");

        // Session mailSession = Session.getDefaultInstance(props, null);

        Session mailSession = Session.getInstance(props, new javax.mail.Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication("username", "password");
            }
        });

        Message msg = new MimeMessage(mailSession);
        msg.setFrom(new InternetAddress(from));
        InternetAddress[] address = { new InternetAddress(to) };
        msg.setRecipients(Message.RecipientType.TO, address);
        msg.setSubject(subject);
        msg.setSentDate(new Date());
        msg.setText(messageText);

        Transport transport = mailSession.getTransport("smtp");

        // connect with authentication
        // transport.connect(host,"myUsername" , "myPassword");

        // connect without authentication
        transport.connect();
        transport.sendMessage(msg, address);

        transport.close();

        System.out.println("Mail was sent to " + to);
        System.out.println(" from " + from);
        System.out.println(" using host " + host + ".");

    }

使用 Telnet 我能够在命令提示符下发送邮件:telnet 邮件主机.xxx 25我收到的回复如下:

220 mailhost Microsoft ESMTP MAIL Service ready at Tue, 29 Mar 201
6 23:34:36 -0700

谷歌搜索后，我还尝试在 Eclipse 中设置 JVM 参数，如下所示，但不幸的是仍然出现如下所示的异常

-Djava.net.preferIPv4Stack=true

异常(exception):

Exception in thread "main" org.apache.commons.mail.EmailException: Sending the email to the following server failed : mailhost.xxx:25
    at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1242)
    at org.apache.commons.mail.Email.send(Email.java:1267)
    at edu.xxx.pageobject.appcenter.util.ReportGenerator.main(ReportGenerator.java:328)
Caused by: javax.mail.MessagingException: Could not connect to SMTP host: mailhost xxx, port: 25;
  nested exception is:
    java.net.SocketException: Permission denied: connect
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1282)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:370)
    at javax.mail.Service.connect(Service.java:297)
    at javax.mail.Service.connect(Service.java:156)
    at javax.mail.Service.connect(Service.java:105)
    at javax.mail.Transport.send0(Transport.java:168)
    at javax.mail.Transport.send(Transport.java:98)
    at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1232)
    ... 2 more
Caused by: java.net.SocketException: Permission denied: connect
    at java.net.TwoStacksPlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    at java.net.Socket.connect(Socket.java:528)
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:232)
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:189)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1250)
    ... 9 more

请告诉我解决上述问题的任何可能的解决方案。

Answer 1

自:

• 源异常指向权限问题，
• 但您可以使用 telnet 从命令行进行连接

这不是网络防火墙问题。

您还排除了相关的Java 7 bug 。因此，问题可能来自您的本地 Windows 防火墙，或您正在使用的任何防病毒/防火墙。它可能会授予 telnet 权限，但不会授予 Java 权限。

尝试禁用所有本地防火墙/防病毒软件，并检查 java 是否可以成功连接。如果是这样，请重新启用防火墙，并创建异常(exception)规则以允许 Java 应用程序连接到端口 25。