Hi there,
we just bought some licences of zimbra version 8.0.1. Its running on CentOS 6.3.
I solved every errors (so many thanks to this forum ), but I dont know what to do with this problem.
We started to use Zimbra Desktop client and there is something wrong with briefcase. I can type and add everything but I cant share.
When I want share file to someone, it says this error:

Code:
An unknown error (mail.TRY_AGAIN) has occurred.
method:        [unknown]
msg:        try again: Unable to connect to the MTA
code:        mail.TRY_AGAIN
detail:        soap:Receiver
trace:        com.zimbra.cs.mailbox.MailServiceException: try again: Unable to connect to the MTA ExceptionId:btpool0-30:1358238660147:c8c0702f23dc07fb Code:mail.TRY_AGAIN at com.zimbra.cs.mailbox.MailServiceException.TRY_AGAIN(MailServiceException.java:484) at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(MailSender.java:628) at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(MailSender.java:425) at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(MailSender.java:385) at com.zimbra.cs.service.mail.SendMsg.doSendMessage(SendMsg.java:191) at com.zimbra.cs.service.mail.SendMsg.handle(SendMsg.java:152) at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEngine.java:412) at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.java:287) at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.java:158) at com.zimbra.soap.SoapServlet.doWork(SoapServlet.java:303) at com.zimbra.soap.SoapServlet.doPost(SoapServlet.java:217) at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) at com.zimbra.cs.servlet.ZimbraServlet.service(ZimbraServlet.java:206) at javax.servlet.http.HttpServlet.service(HttpServlet.java:814) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:390) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:218) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:422) 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(HandlerWrapper.java:152) at org.mortbay.jetty.handler.rewrite.RewriteHandler.handle(RewriteHandler.java:230) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:585) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:988) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:415) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:429) at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:451) Caused by: java.net.ConnectException: Connection refused: connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:317) at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:233) at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1938) at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:642) at javax.mail.Service.connect(Service.java:295) at javax.mail.Service.connect(Service.java:176) at javax.mail.Service.connect(Service.java:125) at com.zimbra.cs.mailbox.MailSender.sendMessageToHost(MailSender.java:898) at com.zimbra.cs.mailbox.MailSender.sendMessage(MailSender.java:831) at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(MailSender.java:565) ... 31 more
request:        

Body: {
  SendMsgRequest: {
    _jsns: "urn:zimbraMail",
    m: {
      e: [
        0: {
          a: "becicka@computersoft.cz",
          add: "0",
          t: "t"
         }
       ],
      mp: [
        0: {
          ct: "multipart/alternative",
          mp: [
            0: {
              content: {
                _content: "The following share has been created:

Shared item: Briefcase (Briefcase)
Owner: local@host.local

Grantee: becicka@computersoft.cz
Role: Admin
Allowed actions: View, Edit, Add, Remove, Administer
"
               },
              ct: "text/plain"
             },
            1: {
              content: {
                _content: "<h3>The following share has been created:</h3>
<p>
<table border="0">
<tr><th align="left">Shared item:</th><td>Briefcase (Briefcase)</td></tr>
<tr><th align="left">Owner:</th><td>local@host.local</td></tr>
</table>
</p>
<table border="0">
<tr><th align="left">Grantee:</th><td>becicka@computersoft.cz</td></tr>
<tr><th align="left">Role:</th><td>Admin</td></tr>
<tr><th align="left">Allowed actions:</th><td>View, Edit, Add, Remove, Administer</td>
</tr>
</table>"
               },
              ct: "text/html"
             },
            2: {
              content: {
                _content: "<share xmlns="urn:zimbraShare" version="0.1" action="new" >
  <grantee id="undefined" email="becicka@computersoft.cz" name="becicka@computersoft.cz" />
  <grantor id="ffffffff-ffff-ffff-ffff-ffffffffffff" email="local@host.local" name="local@host.local" />
  <link id="16" name="Briefcase" view="document" perm="rwidxa" />
  <notes></notes>
</share>"
               },
              ct: "xml/x-zimbra-share"
             }
           ]
         }
       ],
      su: {
        _content: "Share Created: Briefcase shared by local@host.local"
       }
     }
   }
 },
Header: {
  context: {
    _jsns: "urn:zimbra",
    account: {
      _content: "local@host.local",
      by: "name"
     },
    authToken: "(removed)",
    notify: {
      seq: 20
     },
    session: {
      _content: 12,
      id: 12
     },
    userAgent: {
      name: "ZimbraWebClient - PRISM (Win)",
      version: "7.2.1 GA"
     }
   }
 }
I have briefcase just in Desktop version, not in webclient.
I tried check MTA settings in admin panel, and I have hostname as localhost and outbound SMTP server as: smtp.casablanca.cz, (its smtp server of our datacenter), SSL auth is on.
zmcontrol status says that MTA is running. (when restart- nothing happened)

Any idea what to do with this?
thanks a lot for answers