VS里调试可以发出邮件 一切正常
发布到本机的IIS后
System.Net.Mail.SmtpException: 发送邮件失败。 ---> System.Net.Sockets.SocketException: 无法加载或初始化请求的服务提供程序。 在 System.Net.Sockets.Socket..ctor(AddressFamily addressFamily, SocketType socketType, ProtocolType protocolType) 在 System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6) 在 System.Net.PooledStream.Activate(Object owningObject, Boolean async, GeneralAsyncDelegate asyncCallback) 在 System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout) 在 System.Net.Mail.SmtpConnection.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 --- 
什么情况??