发送电子邮件时无法理解RemoteAccessException

Question

突然，在发送电子邮件时在生产服务器上，我得到以下异常堆栈堆栈。我无法在本地处理大约相同的数据时重现此异常。任何想法都表示赞赏

发送电子邮件时出现异常，但不是电子邮件异常类型，例如java.io.IOException RemoteAccessException

org.springframework.remoting.RemoteAccessException: Could not access HTTP invoker remote service at [http://10.0.1.21:8020/cmserver/emailService.remote]; nested exception is java.io.NotSerializableException: com.braintreegateway.BraintreeGateway
    at org.springframework.remoting.httpinvoker.HttpInvokerClientInterceptor.convertHttpInvokerAccessException(HttpInvokerClientInterceptor.java:212)
    at org.springframework.remoting.httpinvoker.HttpInvokerClientInterceptor.invoke(HttpInvokerClientInterceptor.java:145)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy120.composeAndSendSdiEmail(Unknown Source)
    at com.destinations.service.impl.SdiOrderServiceImpl.processVoidOrRefundOrderPayment(SdiOrderServiceImpl.java:238)