Per error instructions: I am listing the error below.
We have checked system load (less than 50% averaging 4%)
The issue seems to be with sending emails that have attachments. The sync errors occur with Outlook (using the connector) or the Zimbra Desktop client.
Details using service:
Debug message: unexpected EOF with 6144 bytes unread

Exception:

com.zimbra.common.service.ServiceException: system failure: InitialSync.syncDocument
ExceptionId:mid=2:1267568378836:284f5281f4883d7e
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:253)
at com.zimbra.cs.mailbox.SyncExceptionHandler.checkRe coverableException(SyncExceptionHandler.java:40)
at com.zimbra.cs.mailbox.InitialSync.syncDocument(Ini tialSync.java:1448)
at com.zimbra.cs.mailbox.InitialSync.syncAllDocuments InFolder(InitialSync.java:1254)
at com.zimbra.cs.mailbox.InitialSync.initialFolderSyn c(InitialSync.java:361)
at com.zimbra.cs.mailbox.InitialSync.prioritySync(Ini tialSync.java:395)
at com.zimbra.cs.mailbox.InitialSync.initialFolderSyn c(InitialSync.java:379)
at com.zimbra.cs.mailbox.InitialSync.initialFolderSyn c(InitialSync.java:385)
at com.zimbra.cs.mailbox.InitialSync.resume(InitialSy nc.java:196)
at com.zimbra.cs.mailbox.InitialSync.resume(InitialSy nc.java:180)
at com.zimbra.cs.mailbox.MailboxSync.sync(MailboxSync .java:186)
at com.zimbra.cs.mailbox.OfflineMailbox.sync(OfflineM ailbox.java:140)
at com.zimbra.cs.mailbox.OfflineMailbox.syncOnTimer(O fflineMailbox.java:121)
at com.zimbra.cs.mailbox.DesktopMailbox$1.run(Desktop Mailbox.java:437)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)
Caused by: java.io.IOException: unexpected EOF with 6144 bytes unread
at com.zimbra.common.util.tar.TarInputStream.read(Tar InputStream.java:353)
at com.zimbra.common.util.tar.TarInputStream.skip(Tar InputStream.java:173)
at com.zimbra.common.util.tar.TarInputStream.getNextE ntry(TarInputStream.java:235)
at com.zimbra.cs.mailbox.InitialSync.syncDocument(Ini tialSync.java:1366)
... 13 more


Any suggestions?

Hesperant