from = “adminaccount@gmail.com”;
Properties props = new Properties();

props.put(“mail.smtp.host”, “smtp.gmail.com”);
props.setProperty(“mail.transport.protocol”, “smtp”);
props.put(“mail.smtp.port”, “465”);
props.put(“mail.smtp.starttls.enable”, “true”);
props.put(“mail.debug”, “true”);
props.put(“mail.smtp.auth”, “true”);
props.put(“mail.smtp.socketFactory.class”, “javax.net.ssl.SSLSocketFactory”);
props.put(“mail.smtp.socketFactory.fallback”, “false”);

Authenticator auth = new MailAuthentication(“useraccount@gmail.com”, “password”);
Session sess = Session.getDefaultInstance(props, auth);

이하 생략.

Could not connect to SMTP host: smtp.gmail.com, port: 465
javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 465;
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.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 kr.or.dasan.user.comn.util.ComnUtil.sendMail(ComnUtil.java:242)
at kr.or.dasan.user.comn.MailThread.run(MailThread.java:42)
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 com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Alerts.java:150)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1584)
at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:174)
at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:168)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:848)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:106)
at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:495)
at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:433)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:877)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1089)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1116)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1100)
at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:548)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:352)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:207)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1938)
… 8 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:221)
at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:145)
at sun.security.validator.Validator.validate(Validator.java:203)
at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:172)
at com.sun.net.ssl.internal.ssl.JsseX509TrustManager.checkServerTrusted(SSLContextImpl.java:320)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:841)
… 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:236)
at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:194)
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:216)
… 24 more

이런 에러가 떨어지면, 아래 첨부된 InstallCert.java를 컴파일 한다.

 InstallCert

> java InstallCert smtp.gmail.com:465 를 실행하면

뭐가 쫘르륵 실행되면서 Enter certificate to add to trusted keystore or ‘q’ to quit: [1] 메세지가 뜨면 Enter.

jssecacerts 라는 파일이 생성이 되는데 JAVA_HOME/jre/lib/security/로 옮겨둔다.

그리고 서버 restart를 하면 메일 전송 성공