This is the error which is copied from /opt/zimbra/log/mailbox.log
2010-03-15 11:57:18,889 INFO [btpool0-9] [name=charlesprem@central.kgisl.com;mid=4;ip=10.100 .1.107;ua=ZimbraWebClient - IE6 (Win)/5.0.19_GA_3083.RHEL5;] SoapEngine - handler exception
com.zimbra.cs.mailbox.MailServiceException: SMTP server reported: 451 4.3.5 Server configuration error
ExceptionId:btpool0-9:1268634438889:65ccc51dc16e757c
Code:mail.SEND_FAILURE Arg

unsent, STR, "charlesprem <charlesprem@kggroup.com>")
at com.zimbra.cs.mailbox.MailServiceException.interna l_SEND_FAILURE(MailServiceException.java:441)
at com.zimbra.cs.mailbox.MailServiceException.SEND_FA ILURE(MailServiceException.java:453)
at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(M ailSender.java:323)
at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(M ailSender.java:120)
at com.zimbra.cs.service.mail.SendMsg.doSendMessage(S endMsg.java:195)
at com.zimbra.cs.service.mail.SendMsg.handle(SendMsg. java:155)
at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEng ine.java:430)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:286)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:160)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:275)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:727)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:187)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1102)
at org.mortbay.servlet.UserAgentFilter.doFilter(UserA gentFilter.java:81)
at org.mortbay.servlet.GzipFilter.doFilter(GzipFilter .java:120)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1093)
at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:361)
at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:716)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:406)
at org.mortbay.jetty.handler.ContextHandlerCollection .handle(ContextHandlerCollection.java:211)
at org.mortbay.jetty.handler.HandlerCollection.handle (HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:139)
at org.mortbay.jetty.handler.rewrite.RewriteHandler.h andle(RewriteHandler.java:350)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:313)
at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:489)
at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:834)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:644)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:205)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:364)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:396)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:442)
Caused by: com.zimbra.cs.mailbox.MailSender$SafeSendFailedExc eption: 451 4.3.5 Server configuration error
; chained exception is:
com.sun.mail.smtp.SMTPAddressFailedException: 451 4.3.5 Server configuration error
at com.sun.mail.smtp.SMTPTransport.rcptTo(SMTPTranspo rt.java:1281)
at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTr ansport.java:622)
at javax.mail.Transport.send0(Transport.java:169)
at javax.mail.Transport.send(Transport.java:98)
at com.zimbra.cs.mailbox.MailSender.sendMessage(MailS ender.java:559)
at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(M ailSender.java:255)
... 33 more