这是应用程序的代码。我一直在尝试使用 eclipse IDE 运行它。我还添加了所有必需的 java 邮件 jar 文件，即 dsn.jar,imap.jar,mailapi.jar,pop3.jar,smtp.jar,mail.jar。 但它给出了以下错误 Could not connect to SMTP host: smtp.gmail.com, port: 587。

没有防火墙阻止访问，因为在 ping smtp.gmail.com 时会收到回复。 我什至尝试过这种方式:

• 首先在您设置/使用客户端的设备上的浏览器中登录 Gmail 帐户
• 转到此处并为“不太安全”的应用程序启用访问权限:https://www.google.com/settings/security/lesssecureapps
• 然后转到这里:https://accounts.google.com/b/0/DisplayUnlockCaptcha然后单击继续。
• 然后立即返回给您的客户并重试。

javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 587; nested exception is: java.net.ConnectException: Connection timed out: connect at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1972) at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:642) at javax.mail.Service.connect(Service.java:317) at javax.mail.Service.connect(Service.java:176) at javax.mail.Service.connect(Service.java:125) at javax.mail.Transport.send0(Transport.java:194) at javax.mail.Transport.send(Transport.java:124) at PlainTextEmailSender.sendPlainTextEmail(PlainTextEmailSender.java:50) at PlainTextEmailSender.main(PlainTextEmailSender.java:73) Caused by: java.net.ConnectException: Connection timed out: connect at java.net.DualStackPlainSocketImpl.connect0(Native Method) at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source) at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source) at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source) at java.net.AbstractPlainSocketImpl.connect(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:319) at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:233) at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1938)

    package net.codejava.mail;

    import java.util.Date;
    import java.util.Properties;

    import javax.mail.Authenticator;
    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 PlainTextEmailSender {

        public void sendPlainTextEmail(String host, String port,
                final String userName, final String password, String toAddress,
                String subject, String message) throws AddressException,
                MessagingException {

            // sets SMTP server properties
            Properties properties = new Properties();
            properties.put("mail.smtp.host", host);
            properties.put("mail.smtp.port", port);
            properties.put("mail.smtp.auth", "true");
            properties.put("mail.smtp.starttls.enable", "true");

            // creates a new session with an authenticator
            Authenticator auth = new Authenticator() {
                public PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(userName, password);
                }
            };

            Session session = Session.getInstance(properties, auth);

            // creates a new e-mail message
            Message msg = new MimeMessage(session);

            msg.setFrom(new InternetAddress(userName));
            InternetAddress[] toAddresses = { new InternetAddress(toAddress) };
            msg.setRecipients(Message.RecipientType.TO, toAddresses);
            msg.setSubject(subject);
            msg.setSentDate(new Date());
            // set plain text message
            msg.setText(message);

            // sends the e-mail
            Transport.send(msg);

        }

        /**
         * Test the send e-mail method
         *
         */
        public static void main(String[] args) {
            // SMTP server information
            String host = "smtp.gmail.com";
            String port = "587";
            String mailFrom = "user_name";
            String password = "password";

            // outgoing message information
            String mailTo = "email_address";
            String subject = "Hello my friend";
            String message = "Hi guy, Hope you are doing well. Duke.";

            PlainTextEmailSender mailer = new PlainTextEmailSender();

            try {
                mailer.sendPlainTextEmail(host, port, mailFrom, password, mailTo,
                        subject, message);
                System.out.println("Email sent.");
            } catch (Exception ex) {
                System.out.println("Failed to sent email.");
                ex.printStackTrace();
            }
        }
    }

最佳答案

对于所有仍在寻找以简单方式解释的答案的人，这里是答案:

第 1 步: 大多数反病毒程序会阻止通过内部应用程序从计算机发送电子邮件。因此，如果您遇到错误，那么您将不得不在调用这些电子邮件发送方法/API 时禁用您的防病毒程序。

第 2 步: 默认情况下禁用对 Gmail 的 SMTP 访问。要允许应用程序使用您的 Gmail 帐户发送电子邮件，请按照以下步骤操作

1. 打开链接:https://myaccount.google.com/security?pli=1#connectedapps
2. 在“安全”设置中，将“允许安全性较低的应用”设置为开启。

第 3 步: 这是我使用过的代码中的一个代码片段，它可以正常工作。 来自 EmailService.java:

private Session getSession() {
    //Gmail Host
    String host = "smtp.gmail.com";
    String username = "techdeveloper.aj@gmail.com";
    //Enter your Gmail password
    String password = "";

    Properties prop = new Properties();
    prop.put("mail.smtp.auth", true);
    prop.put("mail.smtp.starttls.enable", "true");
    prop.put("mail.smtp.host", host);
    prop.put("mail.smtp.port", 587);
    prop.put("mail.smtp.ssl.trust", host);

    return Session.getInstance(prop, new Authenticator() {
        @Override
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(username, password);
        }
    });
}

我还通过这些步骤在 GitHub 上写了一篇博文和一个工作应用程序。请查收:http://softwaredevelopercentral.blogspot.com/2019/05/send-email-in-java.html

关于java - 无法连接到 SMTP 主机 : smtp. gmail.com，端口 : 587; nested exception is: java.net.ConnectException:连接超时:连接，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38608089/