通过 Java 和 Postfix 服务器发送 SMTP 邮件

Question

我正在尝试使用 java 发送 smtp 邮件。我的邮件代码：

    Properties properties = System.getProperties();
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable","true");
    properties.put("mail.smtp.host", "example.com");
    properties.put("mail.smtp.port", "587");
    properties.put("mail.smtp.user", "webmaster@example.com");
    properties.put("mail.smtp.password", "123456");

    Authenticator auth = new Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication("webmaster@example.com","123456");
        }
    };

    Session mailSession = Session.getInstance(properties, auth);
    mailSession.setDebug(true);
    Transport transport = mailSession.getTransport("smtp");

example.com 是我的后缀服务器主机名。

我在此链接中创建了完全相同的步骤： http://cnedelcu.blogspot.com.tr/2014/01/how-to-set-up-simple-mail-server-debian-linux.html

我得到了那个 java 错误：

DEBUG: setDebug: JavaMail version 1.4ea
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "example.com", port 587, isSSL false
220 example.com ESMTP Postfix (Debian/GNU)
DEBUG SMTP: connected to host "example.com", port: 587

EHLO VGate
250-example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "SIZE", arg "10240000"
DEBUG SMTP: Found extension "VRFY", arg ""
DEBUG SMTP: Found extension "ETRN", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "DSN", arg ""
STARTTLS
220 2.0.0 Ready to start TLS
EHLO VGate
14:41:49,841 ERROR SystemUsers:253 - Unknown System ErrSor at REST Service
javax.mail.MessagingException: Can't send command to SMTP host;
  nested exception is:
        javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:1420)
        at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:1408)
        at com.sun.mail.smtp.SMTPTransport.ehlo(SMTPTransport.java:847)
        at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:384)
        at javax.mail.Service.connect(Service.java:275)
        at javax.mail.Service.connect(Service.java:156)

还有我的邮件日志：

Mar  2 14:43:12 VGate postfix/smtpd[28565]: connect from localhost[127.0.0.1]
Mar  2 14:43:12 VGate postfix/smtpd[28565]: SSL_accept error from localhost[127.0.0.1]: 0
Mar  2 14:43:12 VGate postfix/smtpd[28565]: warning: TLS library problem: error:14094416:SSL routines:SSL3_READ_BYTES:sslv3 alert certificate unknown:s3_pkt.c:1294:SSL alert number 46:
Mar  2 14:43:12 VGate postfix/smtpd[28565]: lost connection after STARTTLS from localhost[127.0.0.1]
Mar  2 14:43:12 VGate postfix/smtpd[28565]: disconnect from localhost[127.0.0.1]

我应该怎么做才能克服这些错误。

感谢您的帮助。

Answer 1

您的 JavaMail 实现给您错误，因为它说它找不到受信任的（或由受信任的 CA 签名的）证书。为了修复它，您必须在您的 java 安装中使用“keytool”并将您的服务器的证书添加到受信任的证书列表中：

keytool -import -alias <some alias> -file <your certificate>.cer -keystore cacerts

Answer 2

来自 JavaMail 常见问题解答：

• When connecting to my mail server over SSL I get an exception like "unable to find valid certification path to requested target".

另外，您使用的是非常旧版本的 JavaMail，如果可能，请upgrade。

Answer 3

这对我有用。

import java.util.Properties;

import javax.mail.Message;
import javax.mail.MessagingException;
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 JavaEmail {

    Properties emailProperties;
    Session mailSession;
    MimeMessage emailMessage;

    public static void main(String args[]) throws AddressException,
            MessagingException {

        JavaEmail javaEmail = new JavaEmail();

        javaEmail.setMailServerProperties();
        javaEmail.createEmailMessage();
        javaEmail.sendEmail();
    }

    public void setMailServerProperties() {

        String emailPort = "587";//gmail's smtp port

        emailProperties = System.getProperties();
        emailProperties.put("mail.smtp.port", emailPort);
        emailProperties.put("mail.smtp.auth", "true");
        emailProperties.put("mail.smtp.starttls.enable", "true");

    }

    public void createEmailMessage() throws AddressException,
            MessagingException {
        String[] toEmails = { "xyz@pqr.com" };
        String emailSubject = "Java Email";
        String emailBody = "This is an email sent by JavaMail api.";

        mailSession = Session.getDefaultInstance(emailProperties, null);
        emailMessage = new MimeMessage(mailSession);

        for (int i = 0; i < toEmails.length; i++) {
            emailMessage.addRecipient(Message.RecipientType.TO, new InternetAddress(toEmails[i]));
        }

        emailMessage.setSubject(emailSubject);
        emailMessage.setContent(emailBody, "text/html");//for a html email
        //emailMessage.setText(emailBody);// for a text email

    }

    public void sendEmail() throws AddressException, MessagingException {

        String emailHost = "smtp.gmail.com";
        String fromUser = "your emailid here";//just the id alone without @gmail.com
        String fromUserEmailPassword = "your email password here";

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

        transport.connect(emailHost, fromUser, fromUserEmailPassword);
        transport.sendMessage(emailMessage, emailMessage.getAllRecipients());
        transport.close();
        System.out.println("Email sent successfully.");
    }

}