javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection [duplicate]

Question

I am trying to send a mail from spring application. I have included all the jar files but it is showing this exception:

javax.mail.MessagingException: Exception reading response;
  nested exception is:
    javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?
    at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:1611)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1369)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:412)
    at javax.mail.Service.connect(Service.java:310)
    at javax.mail.Service.connect(Service.java:169)
    at javax.mail.Service.connect(Service.java:118)
    at javax.mail.Transport.send0(Transport.java:188)
    at javax.mail.Transport.send(Transport.java:118)
    at org.symb.leavemanagement.mail.SampleMail.sentMail(SampleMail.java:65)
    at org.symb.leavemanagement.controller.AdminController.processRegistratingUser(AdminController.java:196)
    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:601)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:175)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:421)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:409)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:774)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
Caused by: javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?
    at sun.security.ssl.InputRecord.handleUnknownRecord(InputRecord.java:541)
    at sun.security.ssl.InputRecord.read(InputRecord.java:374)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:893)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1294)
    at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:848)
    at sun.security.ssl.AppInputStream.read(AppInputStream.java:102)
    at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:110)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
    at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:88)
    at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:1589)
    ... 38 more

Answer 1

You are trying to do an SSL connection to a non SSL end-point. If you change that it should work.

I've found that most tutorials about integrating your email with Outlook/Thunderbird/etc call SSL/TSL to a non SSL connection. In general what I've found out there (and this can change but it's the norm) is that only smtp port 465 is SSL. 587 is TSL (no SSL) and 25 is plain.