mailfilter stopps working

[searcher]

Hi,
I am using the latest version of OX.
I installed mailfilter - and it works - at least for a while.
After some time it stops working
The machine on which ox is installed cannot connect to the sieve/mail server any more.
But not only on sieve port. No connections to the sieve/mail server - even ping is not working and runs into time out. But from other pc's the sieve/mail server is available and working. Sieve also works still with Thunderbird-sieve plugin. After stopping all processes and restart on ox it works again for a while.
When I deinstall the mailfilter the problem is gone - but back after installing it.
log from ox:-
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Oct 9, 2012 8:47:10 AM com.openexchange.log.internal.LoggerTask call
SEVERE: Logged at: com.openexchange.groupware.settings.impl.RdbSettin gStorage.readSharedValue(RdbSettingStorage.java:39 8)
Problem while reading setting value.
com.openexchange.ajp13.remoteAddress=127.0.0.1
com.openexchange.session.contextId=1
com.openexchange.session.userId=6
Throwable occurred: IMAP-1016 Category=5 Message=Connection was refused or timed out while attempting to connect to remote server mail.xxx.xxx.de for user yyy. exceptionID=1076810858-84
at com.openexchange.groupware.settings.tree.modules.m ail.folder.Spam$1.getValue(Spam.java:112)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readSharedValue(RdbSettingStorage.java:39 3)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readValues(RdbSettingStorage.java:337)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readSubValues(RdbSettingStorage.java:413)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readValues(RdbSettingStorage.java:333)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readSubValues(RdbSettingStorage.java:413)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readValues(RdbSettingStorage.java:333)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readSubValues(RdbSettingStorage.java:413)
at com.openexchange.groupware.settings.impl.RdbSettin gStorage.readValues(RdbSettingStorage.java:333)
at com.openexchange.multiple.handlers.ConfigFactorySe rvice$ConfigMultipleHandler.performRequest(ConfigF actoryService.java:103)
at com.openexchange.ajax.Multiple.doAction(Multiple.j ava:220)
at com.openexchange.ajax.Multiple.parseActionElement( Multiple.java:178)
at com.openexchange.ajax.Multiple.doPut(Multiple.java :126)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:730)
at com.openexchange.ajax.AJAXServlet.service(AJAXServ let.java:429)
at com.openexchange.ajax.SessionServlet.service(Sessi onServlet.java:259)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at com.openexchange.ajp13.coyote.AjpProcessor.process (AjpProcessor.java:836)
at com.openexchange.ajp13.coyote.sockethandler.Coyote Task.call(CoyoteTask.java:184)
at java.util.concurrent.FutureTask$Sync.innerRun(Futu reTask.java:314)
at java.util.concurrent.FutureTask.run(FutureTask.jav a:149)
at com.openexchange.threadpool.internal.CustomThreadP oolExecutor$Worker.runTask(CustomThreadPoolExecuto r.java:781)
at com.openexchange.threadpool.internal.CustomThreadP oolExecutor$Worker.run(CustomThreadPoolExecutor.ja va:807)
at java.lang.Thread.run(Thread.java:738)
Caused by: IMAP-1016 Category=5 Message=Connection was refused or timed out while attempting to connect to remote server mail.xx.xx.de for user yy. exceptionID=1076810858-83
at com.openexchange.imap.IMAPException.create(IMAPExc eption.java:977)
at com.openexchange.imap.IMAPException.create(IMAPExc eption.java:903)
at com.openexchange.imap.IMAPAccess.checkTemporaryDow n(IMAPAccess.java:1051)
at com.openexchange.imap.IMAPAccess.connectInternal(I MAPAccess.java:777)
at com.openexchange.mail.api.MailAccess.delegateConne ctInternal(MailAccess.java:673)
at com.openexchange.mail.api.MailAccess.connect0(Mail Access.java:631)
at com.openexchange.mail.api.MailAccess.connect(MailA ccess.java:554)
at com.openexchange.mail.MailServletInterfaceImpl.ini tMailAccess(MailServletInterfaceImpl.java:1923)
at com.openexchange.mail.MailServletInterfaceImpl.ini tConnection(MailServletInterfaceImpl.java:1900)
at com.openexchange.mail.MailServletInterfaceImpl.get SpamFolder(MailServletInterfaceImpl.java:1751)
at com.openexchange.groupware.settings.tree.modules.m ail.folder.Spam$1.getValue(Spam.java:106)
... 23 more

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Anybody any idea ??

Joerg

[searcher]

some more info: mailserver is SLES 11SP2 with cyrus-imapd-2.3.11-60.65.64.1
ox server also SLES 11 SP2

[searcher]

SOLVED:
Problem with protocoll inspection on cisco skinny (port 2000) with stopped the communication - switching to port 4190 works.