For the past two weeks, there is an exclamation point next to my Yahoo! mail account in Zimbra Desktop. When I click on it, it states:

Failure communicating with remote server. Please try again later.

Debug message: Unexpected tag in response(expected C15 but got C14)

Exception:

com.zimbra.common.service.ServiceException: system failure: Folder sync failed
ExceptionId:btpool0-4:1303341719878:2d310984c5672c0f
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:248)
at com.zimbra.cs.datasource.imap.ImapSync.importData( ImapSync.java:162)
at com.zimbra.cs.datasource.imap.ImapSync.importData( ImapSync.java:129)
at com.zimbra.cs.offline.OfflineImport.importData(Off lineImport.java:94)
at com.zimbra.cs.offline.YMailImport.importData(YMail Import.java:53)
at com.zimbra.cs.datasource.DataSourceManager.importD ata(DataSourceManager.java:254)
at com.zimbra.cs.datasource.DataSourceManager.importD ata(DataSourceManager.java:219)
at com.zimbra.cs.mailbox.DataSourceMailbox.syncAllLoc alDataSources(DataSourceMailbox.java:430)
at com.zimbra.cs.mailbox.DataSourceMailbox.sync(DataS ourceMailbox.java:460)
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)
Caused by: com.zimbra.common.service.ServiceException: system failure: Synchronization of folder '/Job search' failed
ExceptionId:btpool0-4:1303341719878:2d310984c5672c0f
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:248)
at com.zimbra.cs.datasource.imap.ImapSync.syncFailed( ImapSync.java:360)
at com.zimbra.cs.datasource.imap.ImapSync.syncMessage s(ImapSync.java:301)
at com.zimbra.cs.datasource.imap.ImapSync.syncFolders (ImapSync.java:232)
at com.zimbra.cs.datasource.imap.ImapSync.importData( ImapSync.java:157)
... 35 more
Caused by: com.zimbra.common.service.ServiceException: system failure: Error while fetching message for UID 1050
ExceptionId:btpool0-4:1303341719877:2d310984c5672c0f
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:248)
at com.zimbra.cs.datasource.imap.ImapFolderSync.check CanContinue(ImapFolderSync.java:1111)
at com.zimbra.cs.datasource.imap.ImapFolderSync.fetch Messages(ImapFolderSync.java:783)
at com.zimbra.cs.datasource.imap.ImapFolderSync.fetch Messages(ImapFolderSync.java:678)
at com.zimbra.cs.datasource.imap.ImapFolderSync.syncM essages(ImapFolderSync.java:287)
at com.zimbra.cs.datasource.imap.ImapSync.syncMessage s(ImapSync.java:298)
... 37 more
Caused by: com.zimbra.cs.mailclient.MailException: Unexpected tag in response(expected C15 but got C14)
at com.zimbra.cs.mailclient.imap.ImapRequest.checkSta tus(ImapRequest.java:122)
at com.zimbra.cs.mailclient.imap.ImapRequest.sendChec kStatus(ImapRequest.java:113)
at com.zimbra.cs.mailclient.imap.ImapConnection.uidFe tch(ImapConnection.java:335)
at com.zimbra.cs.mailclient.imap.ImapConnection.uidFe tch(ImapConnection.java:381)
at com.zimbra.cs.mailclient.imap.ImapConnection.uidFe tch(ImapConnection.java:398)
at com.zimbra.cs.datasource.imap.ImapFolderSync.fetch Messages(ImapFolderSync.java:779)
... 40 more

If issue persists please post description and debug information here.