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

Question

A spring mvc app uses JavaMail to connect to dovecot/postfix. Both the spring mvc app and the dovecot/postfix installation are running on the same CentOS 7 physical server box. The app was able to use JavaMail to successfully make an imap connection until just recently, when some scripts for setting up OpenVPN seem to have changed things including the SSL configuration. How can I change the JavaMail code (or other configuration parameters) to get the IMAP connection to work again?

The root error I am currently getting is:

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

The line of code that throws this error is:

store.connect("hostname", "username", "password");

The context of this code is:

Properties props = new Properties();
props.setProperty("mail.imap.starttls.enable", "true");
props.setProperty("mail.store.protocol", "imap");
props.setProperty("mail.imap.partialfetch", "false");
String dirStart = "/home/import/xml/xmlimporttest/";
try {
    Session session = Session.getInstance(props, null);
    session.setDebug(true);
    Store store = session.getStore();
    store.connect("hostname", "username", "password");
    Folder inbox = store.getFolder("INBOX");  
    //other stuff
} catch....

The complete stack trace is:

DEBUG: setDebug: JavaMail version 1.5.0-b01
DEBUG: getProvider() returning javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Oracle]
DEBUG IMAP: mail.imap.partialfetch: false
DEBUG IMAP: mail.imap.ignorebodystructuresize: false
DEBUG IMAP: mail.imap.statuscachetimeout: 1000
DEBUG IMAP: mail.imap.appendbuffersize: -1
DEBUG IMAP: mail.imap.minidletime: 10
DEBUG IMAP: enable STARTTLS
DEBUG IMAP: trying to connect to host "mydomain.com", port 143, isSSL false
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS LOGINDISABLED] Dovecot ready.
DEBUG IMAP: protocolConnect login, host=mydomain.com, user=username, password=<non-null>
A0 STARTTLS  
A0 OK Begin TLS negotiation now.
DEBUG IMAP: STARTTLS Exception, THROW:
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable$
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1904)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:279)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:273)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1446)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:209)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:901)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:837)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1023)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1332)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1359)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1343)
    at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:527)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:464)
    at com.sun.mail.iap.Protocol.startTLS(Protocol.java:388)
    at com.sun.mail.imap.protocol.IMAPProtocol.startTLS(IMAPProtocol.java:820)
    at com.sun.mail.imap.IMAPStore.login(IMAPStore.java:697)
    at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:642)
    at javax.mail.Service.connect(Service.java:295)
    at javax.mail.Service.connect(Service.java:176)        at com.hpp.kp.web.HL7PatientController.processInbox(HL7PatientController.java:1373)
    at com.hpp.kp.web.HL7PatientController.processEmailInbox(HL7PatientController.java:118)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:618)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.github.dandelion.datatables.core.web.filter.DatatablesFilter.doFilter(DatatablesFilter.java:73)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.github.dandelion.datatables.extras.servlet2.filter.DatatablesFilter.doFilter(DatatablesFilter.java:71)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.github.dandelion.datatables.core.web.filter.DatatablesFilter.doFilter(DatatablesFilter.java:73)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.github.dandelion.datatables.extras.servlet2.filter.DatatablesFilter.doFilter(DatatablesFilter.java:71)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57)
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:537)
    at org.apache.coyote.ajp.AbstractAjpProcessor.process(AbstractAjpProcessor.java:831)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:658)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1556)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1513)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certificati$
    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:1428)
    ... 101 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)
    ... 107 more
javax.mail.MessagingException: STARTTLS failure;
  nested exception is:
    com.sun.mail.iap.ProtocolException: STARTTLS failure
    at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:668)
    at javax.mail.Service.connect(Service.java:295)
    at javax.mail.Service.connect(Service.java:176)
    at com.hpp.kp.web.HL7PatientController.processInbox(HL7PatientController.java:1373)
    at com.hpp.kp.web.HL7PatientController.processEmailInbox(HL7PatientController.java:118)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:618)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.github.dandelion.datatables.core.web.filter.DatatablesFilter.doFilter(DatatablesFilter.java:73)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.github.dandelion.datatables.extras.servlet2.filter.DatatablesFilter.doFilter(DatatablesFilter.java:71)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:537)
    at org.apache.coyote.ajp.AbstractAjpProcessor.process(AbstractAjpProcessor.java:831)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:658)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1556)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1513)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: com.sun.mail.iap.ProtocolException: STARTTLS failure
    at com.sun.mail.imap.protocol.IMAPProtocol.startTLS(IMAPProtocol.java:834)
    at com.sun.mail.imap.IMAPStore.login(IMAPStore.java:697)
    at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:642)
    ... 88 more
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderExcept$
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1904)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:279)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:273)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1446)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:209)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:901)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:837)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1023)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1332)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1359)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1343)
    at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:527)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:464)
    at com.sun.mail.iap.Protocol.startTLS(Protocol.java:388)
    at com.sun.mail.imap.protocol.IMAPProtocol.startTLS(IMAPProtocol.java:820)
    ... 90 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certificati$
    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:1428)
    ... 101 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)
    ... 107 more  

EDIT

As per @jCoder's suggestion, I typed export JAVA_OPTS=-Djavax.net.debug=all before running startup.sh and then clicking the link in the app that triggers the imap login request that throws the error. The same stack trace as above was thrown, but the new debug instructions caused 1100+ lines of relevant additional output in the catalina.out logs. I have uploaded these additional logs to a file sharing site, and you can view the additional logs by clicking on this link .

Answer 1

The SSL certificate isn't trusted by Java. The certificate may be self-signed, or it may be signed by a CA (Certificate Authority) whose root certificate is not in the Java certificate store. The set of root certificates known by Java isn't as extensive as the set that your web browser knows about.

Assuming you do indeed trust the certificate in question, you can add it to the Java certificate store (which is called cacerts ) using the keytool command. For example (change paths as appropriate for your installation and OS):

keytool -import -trustcacerts -file NewRootCACertificate.crt -keystore "C:\\Program Files\\Java\\jre1.8.0_31\\lib\\security\\cacerts"

By default the cacerts keystore has a password of changeit .

UPDATE:

Problem resolved to a working system in chat, although not with ideal configuration.

• It looks like the previously working set-up was not using SSL.
• This set-up stopped working, perhaps because of software updates changing the configuration (my speculation) to prevent login in the plain.
• starttls was switched on to address the inability to login in the plaintext IMAP mode.
• The lack of suitably-trusted certificate then emerged as an issue, hence the error in the question.
• The certificate that was there (probably default created during installation of the mail server) didn't have the right domain name in the Common Name, but even with a fresh certificate, and adding it to what seemed to be the right cacerts key store (the key store path was mentioned in the application logs) the client failed to trust the certificate. We never got to the bottom of that.
• Working set-up was arrived at with the following configuration (ie trusting the server by hostname and connecting directly with SSL rather than using starttls ):
  • props.setProperty("mail.imap.ssl.enable", "true");
  • props.setProperty("mail.imap.ssl.trust", "mydomain.com");

This isn't ideal, however the client application is running on the same machine as the IMAP server, so this is probably not a huge risk.

In the long run, you may want to make a note that you did this work-around, and see whether you can get the certificate verification happening by other means, possibly a custom certificate verification handler or explicitly specifying the certificate store.

Answer 2

• You should import certificate of the server:port to java JRE keystore for example for following server and port:

   serverAddress myserver.mydomain.com serverPort 443 keystore default password did not changed, so it is **changeit** if you changed it use yours as password. 

• First of all, check $JAVA_HOME and java executable before continue, you should be sure about the choosing correct JAVA_HOME for importing , if you have different ones:

   $ ~/bin$ echo $JAVA_HOME /opt/jdk $ ~/bin$ which java /usr/bin/java $ ~/bin$ ls -l /usr/bin/java lrwxrwxrwx 1 root root 22 May 10 2014 /usr/bin/java -> /etc/alternatives/java $ ~/bin$ ls -l /etc/alternatives/java lrwxrwxrwx 1 root root 17 Jun 6 2014 /etc/alternatives/java -> /opt/jdk/bin/java $ ~/bin$ java -version java version "1.8.0_05" Java(TM) SE Runtime Environment (build 1.8.0_05-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode) $ ~/bin$ `which java` -version java version "1.8.0_05" Java(TM) SE Runtime Environment (build 1.8.0_05-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode) $ ~/bin$ $JAVA_HOME/bin/java -version java version "1.8.0_05" Java(TM) SE Runtime Environment (build 1.8.0_05-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode) 

• Extracting certificate from the server:

   $ openssl s_client -connect <serverAddress:serverPort> 2>&1 < "/" | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /tmp/myserver.crt 

  For this example <serverAddress:serverPort> should be replaced with myserver.mydomain.com:443

• The extracted file should be look like as follows:

   $ cat /tmp/myserver.crt -----BEGIN CERTIFICATE----- blahblahblahaC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQCd ME22AKpyBPIRbTwTBedJz/KFtwCAxO2jXIcIob99LXv8W4KMOJgazn2UUBm/azZ1 z+9qhq3UeIy8Z58WK2N5l/SI7s3+bkii/dnpW3Akw8OyXABnN1EyfwnL607POqXm blahblahblah ...Certificate Data is variable for each server address... blahblahblah blahblahblahT9p1jar2vxoHv3/dSwKoeLL8XpkmVx9oVUZ3XuICPvEmu8eBfOEm ZXNlYXJjaC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQCd4I7L ME22AKpyBPIRbTwTBedJz/KFtwCAxO2jXIcIob99LXv8W4KMOJgazn2UUBm/azZ1 -----END CERTIFICATE----- 

• You need to import the extracted certificate into JRE keystore:

   $ keytool -import -alias myserverCert -file /tmp/myserver.crt -keystore $JAVA_HOME/jre/lib/security/cacerts 

• You can check that the certification existence in java JRE keystore or not after the import:

    $ keytool -list -keystore $JAVA_HOME/jre/lib/security/cacerts 

• Default password for java JRE keystore is

  changeit

• For applying the changes you need to restart the java JVM.

• After finish you can remove the temporary file if you had created it in a non temporary place:

   $ rm /tmp/myserver.crt 

• for your case you can do entire this process two times onetime before VPN establishment and onetime after establishment only you should to use two alias for each time as follows:

   # Before VPN Connect $ openssl s_client -connect myserver.mydomain.com:443 2>&1 < "/" | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /tmp/myserver.crt $ keytool -import -alias myserverCert -file /tmp/myserver.crt -keystore $JAVA_HOME/jre/lib/security/cacerts # After VPN Connect $ openssl s_client -connect myserver.mydomain.com:443 2>&1 < "/" | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /tmp/myserver-vpn.crt $ keytool -import -alias myserverVPNCert -file /tmp/myserver-vpn.crt -keystore $JAVA_HOME/jre/lib/security/cacerts 

  If two extracted certificates are same the problem is another thing and you should find another solution.

   $ diff /tmp/myserver.crt /tmp/myserver-vpn.crt 

I hope this can help you