My Java program stopped sending emails using my gmail Account

Question

I searched several related posts here and in other places, but none of them solved my problem. I have a program that sends emails to a set of people using "javamail API". It worked fine once. Today I needed again, but I cannot send any email... My sendEmail method is the following:

public void sendEmail(String userName, String password, String toAddress, 
       String subject, String message, String[] attachFiles) 
       throws AddressException, MessagingException {

     // sets SMTP properties
    Properties properties = new Properties();
    properties.put("mail.smtp.host", "smtp.gmail.com");
    properties.put("mail.smtp.port", "587");
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable", "true");
    properties.put("mail.user", userName);
    properties.put("mail.password", password);

    // creates a new session with an authenticator
    Authenticator auth = new SMTPAuthenticator(userName, password);
    Session session = Session.getInstance(properties, auth);

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

    try {
        msg.setFrom(new InternetAddress(userName, "My name"));
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    InternetAddress[] toAddresses = {new InternetAddress(toAddress)};        
    msg.setRecipients(Message.RecipientType.TO, toAddresses);
    msg.setSubject(subject);
    msg.setSentDate(new Date());

    // creates message part
    MimeBodyPart messageBodyPart = new MimeBodyPart();
    messageBodyPart.setContent(message, "text/html");

    // creates multi-part
    Multipart multipart = new MimeMultipart();
    multipart.addBodyPart(messageBodyPart);       

    // adds attachments
    if (attachFiles != null && attachFiles.length > 0) {
        for (String filePath : attachFiles) {
            addAttachment(multipart, filePath);
        }
    }

    // sets the multi-part as e-mail's content
    msg.setContent(multipart);

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

}

So, now the attempt to call this method I got the following error (I'm using jdk 1.7.0_21):

Sending email Failed...

javax.mail.MessagingException: Could not convert socket to TLS;
  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.startTLS(SMTPTransport.java:1907)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:666)
    at javax.mail.Service.connect(Service.java:367)
    at javax.mail.Service.connect(Service.java:226)
    at javax.mail.Service.connect(Service.java:175)
    at javax.mail.Transport.send0(Transport.java:253)
    at javax.mail.Transport.send(Transport.java:124)
    at EmailSender.sendEmail(EmailSender.java:86)
    at CFP_LaWasp_EmailSender.sendCFPLaWasp(CFP_LaWasp_EmailSender.java:178)
    at CFP_LaWasp_EmailSender.main(CFP_LaWasp_EmailSender.java:220)
Caused by: 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 sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1886)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:276)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:270)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1341)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:153)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:868)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:804)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1016)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1312)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1339)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1323)
    at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:528)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:465)
    at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:1902)
    ... 9 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
    at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
    at sun.security.validator.Validator.validate(Validator.java:260)
    at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:326)
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:126)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1323)
    ... 19 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:196)
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:268)
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
    ... 25 more

I don't know how to solve this issue, since it used to work before... Also, I don't know if my Gmail has something to do with this (if it blocked this access...)

I appreciate any help.

Answer 1

I had this problem with java 8. After updating this property problem solved

properties.put("mail.smtp.ssl.trust", "smtp.gmail.com")

if used spring boot in application.property

spring.mail.properties.mail.smtp.ssl.trust = smtp.gmail.com

Answer 2

I have been struggling with this error for several hours. I have tried to install the Server certificates using the answer provided by Bil Shannon. Nothing worked.

My problem was AVAST Antivirus. Once I have disabled Avast Mail Shield, I was able to send mails via gmail account from my web app.

Answer 3

The key error is this:

Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

See this JavaMail FAQ entry.

Since you're connecting to Gmail, this shouldn't happen. The most likely causes are:

• There's a firewall or anti-virus program intercepting your request.
• There's something wrong in your JDK installation preventing it from finding the trusted certificate authorities
• You're running in an application server that has overridden the JDK's list of trusted certificate authorities

Answer 4

I've been solved my problem with:

properties.put("mail.smtp.ssl.trust", "smtp.gmail.com")

and when I'm using spring boot

spring.mail.properties.mail.smtp.ssl.trust = smtp.gmail.com