Zimbra cannot acces external account pop3

[n1co38]

I have multiple zimbra accounts which I have set up with external accounts on another server (Mdaemon). I use POP3 to access these accounts. Everithing was Ok at the begining, but now i cannot synchronise email with this external account, when i make a test in external account i have 'access denied'.

Mailbox.log :

2011-03-28 12:02:49,142 INFO [btpool0-3://192.168.21.110/service/soap/TestDataSourceRequest] [name=user@user;mid=13;ip=192.168.168.161;ua=Zimbra WebClient - SAF3 (Win)/7.0.0_GA_3077;] datasource - Testing: DataSource: { id=TestId, type=pop3, isEnabled=false, name=Test, host=pop.user, port=110, connectionType=cleartext, username=user@user, folderId=-1 }
2011-03-28 12:02:50,071 WARN [btpool0-3://192.168.21.110/service/soap/TestDataSourceRequest] [name=mario.morciano@sarenne-motors.ch;mid=13;ip=192.168.168.161;ua=ZimbraWebCl ient - SAF3 (Win)/7.0.0_GA_3077;] datasource - Test failed: DataSource: { id=TestId, type=pop3, isEnabled=false, name=Test, host=pop.sarenne-motors.ch, port=110, connectionType=cleartext, username=user@user, folderId=-1 }
com.zimbra.common.service.ServiceException: system failure: Unable to connect to POP3 server: DataSource: { id=TestId, type=pop3, isEnabled=false, name=Test, host=pop.user, port=110, connectionType=cleartext, username=username=user@user, folderId=-1 }
ExceptionId:btpool0-3://192.168.21.110/service/soap/TestDataSourceRequest:1301306570071:75721dd5d7efbf 3b
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:248)
at com.zimbra.cs.datasource.Pop3Sync.connect(Pop3Sync .java:156)
at com.zimbra.cs.datasource.Pop3Sync.test(Pop3Sync.ja va:109)
at com.zimbra.cs.datasource.DataSourceManager.test(Da taSourceManager.java:208)
at com.zimbra.cs.service.mail.TestDataSource.handle(T estDataSource.java:129)
at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEng ine.java:401)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:276)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:157)
at com.zimbra.soap.SoapServlet.doWork(SoapServlet.jav a:294)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:215)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:727)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:208)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:511)

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$RequestHandler.co ntent(HttpConnection.java:946)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:405)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:410)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:451)
Caused by: javax.security.auth.login.LoginException: access denied
at com.zimbra.cs.datasource.Pop3Sync.connect(Pop3Sync .java:152)
... 38 more
2011-03-28 12:02:55,059 INFO [MailboxPurge] [name=ham.gwmqghs3p@hbg-mail;mid=7;] purge - Purging messages.
2011-03-28 12:03:55,070 INFO [MailboxPurge] [name=user@users;mid=13;] purge - Purging messages.


Release 7.0.0_GA_3077.UBUNTU10_64 UBUNTU10_64 FOSS edition.

sorry for my english !

And thank you in advance !