Tangosol is trying to store Email object and NotSerializableException is thrown

2007-07-30 15:54:43,031 DEBUG [http-8080-Processor4] [workflow.macros.actions.AbstractActionMacro] logMessage Error
 -- url: /confluence/plugins/approvalsworkflow/save.action | userName: auctor | action: save
(Wrapped) java.io.NotSerializableException: com.atlassian.mail.Email
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1075)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1369)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1341)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1284)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1073)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1369)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1341)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1284)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1073)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:291)
        at com.tangosol.util.ExternalizableHelper.writeSerializable(ExternalizableHelper.java:2100)
        at com.tangosol.util.ExternalizableHelper.internalWriteObject(ExternalizableHelper.java:2481)
        at com.tangosol.util.ExternalizableHelper.toBinary(ExternalizableHelper.java:166)
        at com.tangosol.coherence.component.util.daemon.queueProcessor.service.ReplicatedCache.requestUpdate(ReplicatedCache.CDB:21)
        at com.tangosol.coherence.component.util.daemon.queueProcessor.service.ReplicatedCache.updateResource(ReplicatedCache.CDB:68)
        at com.tangosol.coherence.component.util.CacheHandler.put(CacheHandler.CDB:11)
        at com.tangosol.coherence.component.util.CacheHandler.put(CacheHandler.CDB:1)
        at com.tangosol.coherence.component.util.SafeNamedCache.put(SafeNamedCache.CDB:1)
        at com.atlassian.confluence.cluster.tangosol.TangosolClusteredFifoBuffer.add(TangosolClusteredFifoBuffer.java:65)
        at com.atlassian.core.task.AbstractTaskQueue.addTask(AbstractTaskQueue.java:73)
        at com.atlassian.core.task.AbstractErrorQueuedTaskQueue.addTask(AbstractErrorQueuedTaskQueue.java:75)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:284)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:163)
        at $Proxy44.addTask(Unknown Source)
        at com.atlassian.core.task.DefaultMultiQueueTaskManager.addTask(DefaultMultiQueueTaskManager.java:58)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:284)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:163)
        at $Proxy52.addTask(Unknown Source)
        at com.comalatech.confluence.workflow.macros.actions.SendEmailMacro.execute(SendEmailMacro.java:88)

    MultiQueueTaskManager taskManager;
    ...
    Email emailMessage = new Email(address);
    emailMessage.setBody(wikiMessage);
    emailMessage.setMimeType("text/html");
    emailMessage.setSubject(subject);
    SingleMailQueueItem queueItem = new SingleMailQueueItem(emailMessage);
    taskManager.addTask("mail",queueItem);