Error sending email

messages stopped in outbox, follows log: Detail, my email is alexfrnds@yahoo.com.au but I configured my account with alexfrnds and it completed with yahoo.com:

2008-07-30 10:46:02,998 INFO [sync-timer-alexfrnds@yahoo.com] [] offline - YMail send failure: teste
java.io.IOException: Request failed
at com.zimbra.cs.offline.util.ymail.YMailClient.reque stFailed(YMailClient.java:415)
at com.zimbra.cs.offline.util.ymail.YMailClient.sendM essage(YMailClient.java:125)
at com.zimbra.cs.offline.YMailSender.sendMessage(YMai lSender.java:58)
at com.zimbra.cs.mailbox.MailSender.sendMimeMessage(M ailSender.java:253)
at com.zimbra.cs.mailbox.LocalMailbox.sendPendingMess ages(LocalMailbox.java:166)
at com.zimbra.cs.mailbox.LocalMailbox.sync(LocalMailb ox.java:356)
at com.zimbra.cs.mailbox.LocalMailbox.syncOnTimer(Loc alMailbox.java:282)
at com.zimbra.cs.mailbox.DesktopMailbox$1.run(Desktop Mailbox.java:117)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Caused by: javax.xml.ws.soap.SOAPFaultException
at com.sun.xml.ws.fault.SOAP11Fault.getProtocolExcept ion(SOAP11Fault.java:188)
at com.sun.xml.ws.fault.SOAPFaultBuilder.createExcept ion(SOAPFaultBuilder.java:122)
at com.sun.xml.ws.client.sei.SyncMethodHandler.invoke (SyncMethodHandler.java:119)
at com.sun.xml.ws.client.sei.SyncMethodHandler.invoke (SyncMethodHandler.java:89)
at com.sun.xml.ws.client.sei.SEIStub.invoke(SEIStub.j ava:118)
at $Proxy34.sendMessage(Unknown Source)
at com.zimbra.cs.offline.util.ymail.YMailClient.sendM essage(YMailClient.java:123)
... 8 more
2008-07-30 10:46:02,998 DEBUG [sync-timer-alexfrnds@yahoo.com] [] offline - Loading yauth tokens for account 'fc6d5431-375e-4285-835e-014cf49fdb27'