Email send not working: No provider for SMTP

Hi Guys,

We are using Quality center on site and what we are finding is the tool is unable to send emails after abount an hour or so after restarting the service or rebooting. When we first reboot emails are send without issue. The error that is being thrown is below.
I'm hoping someone can work out from this error so possible causes. The fact that it does work initially we suspect that Quality center is setup correctly to send emails. The error is below. Any help or ideas would be appreciated

Messages:
Failed to mail the specified entities; Failed to mail the specified entities; Failed to send mail to 'David.xxxxl@xxxx.gov.au' ; Failed to send the message via mail server 'exchangerelay.prod.csanet.gov.au'; No provider for SMTP; No provider for SMTP;

Stack Trace:
javax.mail.NoSuchProviderException: No provider for SMTP
at javax.mail.Session.getProvider(Session.java:455)
at javax.mail.Session.getTransport(Session.java:650)
at javax.mail.Session.getTransport(Session.java:631)
at javax.mail.Session.getTransport(Session.java:617)
at com.mercury.optane.core.mail.CMailService.sendMail(CMailService.java:496)
wrapped in com.mercury.optane.core.CTdException: No provider for SMTP
at com.mercury.optane.core.mail.CMailService.sendMail(CMailService.java:545)
at com.mercury.optane.core.mail.CMailService.sendMail(CMailService.java:489)
at com.mercury.td.tdserver.mail.MailLogic.sendMessage(MailLogic.java:1629)
wrapped in com.mercury.optane.core.CTdException: Failed to send the message via mail server 'exchangerelay.prod.xxxx.gov.au'
at com.mercury.td.tdserver.mail.MailLogic.sendMessage(MailLogic.java:1631)
at com.mercury.td.tdserver.mail.MailLogic.sendMail(MailLogic.java:778)
wrapped in com.mercury.optane.core.CTdException: Failed to send mail to 'David.xxxx@xxxx.gov.au'
at com.mercury.td.tdserver.mail.MailLogic.sendMail(MailLogic.java:782)
at com.mercury.td.tdserver.mail.MailLogic.sendEntity(MailLogic.java:708)
wrapped in com.mercury.optane.core.CTdException: Failed to mail the specified entities
at com.mercury.td.tdserver.mail.MailLogic.sendEntity(MailLogic.java:711)
at com.mercury.td.tdserver.mail.MailLogic.sendEntity(MailLogic.java:538)
wrapped in com.mercury.optane.core.CTdException: Failed to mail the specified entities
at com.mercury.td.tdserver.mail.MailLogic.sendEntity(MailLogic.java:555)
at com.mercury.td.tdserver.requests.MailEntity.execute(MailEntity.java:36)
at com.mercury.optane.core.web.RequestsDispatcher.execute(RequestsDispatcher.java:91)
at com.mercury.td.web.CAbsServlet.executeFunction(CAbsServlet.java:486)
at com.mercury.td.web.CAbsServlet.processRequest(CAbsServlet.java:478)
at com.mercury.td.web.CTdServlet.processRequest(CTdServlet.java:165)
at com.mercury.td.web.CAbsServlet.doPost(CAbsServlet.java:352)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.hp.qc.core.utils.gzipfilter.GZIPFilter.doFilter(GZIPFilter.java:30)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.mercury.optane.core.state.ServerStatusFilter.doFilter(ServerStatusFilter.java:33)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:598)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)