Problems sending mail with Confluence

Probably this one is somehow related to JRA-11902.
Trying to send a test mail via Confluence I would get

An error has occurred with sending the test email:
java.lang.IllegalArgumentException: Mail server at location [java:comp/env/mail/ConfluenceMailServer] is not of required type javax.mail.Session.
at com.atlassian.mail.server.impl.SMTPMailServerImpl.getSession(SMTPMailServerImpl.java:112)
at com.atlassian.mail.server.impl.SMTPMailServerImpl.send(SMTPMailServerImpl.java:161)
at com.atlassian.confluence.admin.actions.mail.SendTestEmailAction.execute(SendTestEmailAction.java:52)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.intercept(DefaultWorkflowInterceptor.java:55)
at com.atlassian.confluence.core.ConfluenceWorkflowInterceptor.intercept(ConfluenceWorkflowInterceptor.java:39)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.atlassian.confluence.core.ConfluenceValidationInterceptor.intercept(ConfluenceValidationInterceptor.java:16)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:47)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.pages.actions.PageAwareInterceptor.intercept(PageAwareInterceptor.java:114)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.spaces.actions.SpaceAwareInterceptor.intercept(SpaceAwareInterceptor.java:67)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.core.actions.LastModifiedInterceptor.intercept(LastModifiedInterceptor.java:39)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.core.ConfluenceAutowireInterceptor.intercept(ConfluenceAutowireInterceptor.java:25)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.xwork.interceptors.XWorkTransactionInterceptor.intercept(XWorkTransactionInterceptor.java:98)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:115)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:229)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:199)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:117)
at com.atlassian.confluence.util.profiling.ProfilingPageFilter.parsePage(ProfilingPageFilter.java:137)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:51)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.core.filters.ServletContextThreadLocalFilter.doFilter(ServletContextThreadLocalFilter.java:21)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.confluence.util.UserThreadLocalFilter.doFilter(UserThreadLocalFilter.java:44)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:182)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:159)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.confluence.util.ClusterHeaderFilter.doFilter(ClusterHeaderFilter.java:35)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:172)
at com.atlassian.spring.filter.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:29)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:122)
at com.atlassian.core.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:27)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.confluence.util.RequestCacheThreadLocalFilter.doFilter(RequestCacheThreadLocalFilter.java:25)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.core.filters.gzip.GzipFilter.doFilter(GzipFilter.java:61)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:37)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)

I've done what's described at http://www.atlassian.com/software/jira/docs/v3.7/smtpconfig.html meaning that javamail.jar and activation.jar are located at Tomcat lib folder and don't duplicate.