I sync mail from zimbra proxy node. i test click go to offline icon and then i click go to online icon.
zimbra desktop show status error, unknow last sync.

Debug message: error while proxying request to target server: HTTP/1.1 302 Moved Temporarily

Exception:

com.zimbra.common.service.ServiceException: error while proxying request to target server: HTTP/1.1 302 Moved Temporarily
ExceptionId:sync-mbox-zsrichock@vpls.net:1365135921415:cdd8cc879a1d44c6
Code:service.PROXY_ERROR Argurl, STR, "https://172.16.100.5/service/soap/NoOpRequest")
at com.zimbra.common.service.ServiceException.PROXY_E RROR(ServiceException.java:322)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:247)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:164)
at com.zimbra.common.soap.SoapTransport.invoke(SoapTr ansport.java:407)
at com.zimbra.common.soap.SoapTransport.invokeWithout Session(SoapTransport.java:393)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:678)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:640)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:635)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:628)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:624)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:620)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:616)
at com.zimbra.cs.mailbox.InitialSync.resume(InitialSy nc.java:216)
at com.zimbra.cs.mailbox.InitialSync.resume(InitialSy nc.java:211)
at com.zimbra.cs.mailbox.MailboxSync.sync(MailboxSync .java:190)
at com.zimbra.cs.mailbox.ZcsMailbox.sync(ZcsMailbox.j ava:124)
at com.zimbra.cs.mailbox.ZcsMailbox.syncOnTimer(ZcsMa ilbox.java:105)
at com.zimbra.cs.mailbox.SyncMailbox$1.run(SyncMailbo x.java:279)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)

If issue persists please post description and debug information here.