为什么服务器上会报错？
日志如下
System.Net.Mail.SmtpException: 发送邮件失败。 ---> System.IO.IOException: 由于远程方已关闭传输流，身份验证失败。
在 System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
在 System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
在 System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
在 System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
在 System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
在 System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
在 System.Net.TlsStream.CallProcessAuthentication(Object state)
在 System.Threading.ExecutionContext.runTryCode(Object userData)
在 System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
在 System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
在 System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
在 System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
在 System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
在 System.Net.Mail.SmtpConnection.Flush()
在 System.Net.Mail.ReadLinesCommand.Send(SmtpConnection conn)
在 System.Net.Mail.EHelloCommand.Send(SmtpConnection conn, String domain)
在 System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
在 System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)
在 System.Net.Mail.SmtpClient.GetConnection()
在 System.Net.Mail.SmtpClient.Send(MailMessage message)
--- 内部异常堆栈跟踪的结尾 ---
在 System.Net.Mail.SmtpClient.Send(MailMessage message)
