error while proxying request to target server: HTTP/1.1 504 Unknown Host Exception:

com.zimbra.common.service.ServiceException: error while proxying request to target server: HTTP/1.1 504 Unknown Host
ExceptionId:btpool0-0:1328179459301:111501529086e418
Code:service.PROXY_ERROR Argurl, STR, "https://inmumzm01.tcs.com/service/soap/SyncRequest")
at com.zimbra.common.service.ServiceException.PROXY_E RROR(ServiceException.java:309)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:240)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:162)
at com.zimbra.common.soap.SoapTransport.invoke(SoapTr ansport.java:356)
at com.zimbra.common.soap.SoapTransport.invokeWithout Session(SoapTransport.java:342)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:665)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:627)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:622)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:615)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:611)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:607)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:603)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequestWithNo tification(ZcsMailbox.java:599)
at com.zimbra.cs.mailbox.DeltaSync.sync(DeltaSync.jav a:85)
at com.zimbra.cs.mailbox.DeltaSync.sync(DeltaSync.jav a:73)
at com.zimbra.cs.mailbox.MailboxSync.sync(MailboxSync .java:178)
at com.zimbra.cs.mailbox.ZcsMailbox.sync(ZcsMailbox.j ava:119)
at com.zimbra.cs.service.offline.OfflineSync.handle(O fflineSync.java:44)
at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEng ine.java:420)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:274)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:158)
at com.zimbra.soap.SoapServlet.doWork(SoapServlet.jav a:291)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:212)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:727)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:181)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:390)
at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:418)
at org.mortbay.jetty.handler.ContextHandlerCollection .handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle (HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152)
at org.mortbay.jetty.handler.rewrite.RewriteHandler.h andle(RewriteHandler.java:230)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:543)
at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:939)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:755)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:405)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:413)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:451)