c#之问题是关于在 ASP.NET 中发送电子邮件

protected void SendEmail(object sender, EventArgs e) 
    { 
        SmtpClient smtpClient = new SmtpClient(); 
        MailMessage message = new MailMessage(); 
        try 
        { 
            MailAddress fromAddress = new MailAddress("fromemail", "From Me"); 
            MailAddress toAddress = new MailAddress("toemail", "To You"); 
            message.From = fromAddress; 
            message.To.Add(toAddress); 
            message.Subject = "Testing!"; 
            message.Body = "This is the body of a sample message"; 
            smtpClient.Host = "smtp.host.com"; 
            smtpClient.Credentials = new System.Net.NetworkCredential("username", "password"); 
            smtpClient.EnableSsl = true; 
            smtpClient.Port = 587; 
            smtpClient.Send(message); 
            statusLabel.Text = "Email sent."; 
        } 
        catch (Exception ex) 
        { 
            statusLabel.Text = "Coudn't send the message!\n"+ex.Message; 
        } 
    } 

错误是

"Failure sending mail."

我不能发送任何。 有什么问题？

内部异常是

System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: 连接尝试失败，因为连接方在一段时间后没有正确响应，或者建立的连接失败因为连接的主机未能在 System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) 在 System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP) 在 System.Net.ServicePoint 响应 74.125.39.109:587。 ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception) --- 内部异常堆栈跟踪结束 --- 在 System.Net.ServicePoint.GetConnection( PooledStream PooledStream，对象所有者， bool 异步，IPAddress＆地址，Socket＆abortSocket，Socket＆abortSocket6，Int32超时)在System.Net.PooledStream.Activate(对象owningObject， bool 异步，Int32超时，GeneralAsyncDelegate asyncCallback)在System.Net.PooledStream.Activate (对象 owningObject，GeneralAsyncDelegate asyncCallback)在 System.Net.ConnectionPool.GetConnection(对象 owningObject，GeneralAsyncDelegate asyncCallback，Int32 creationTimeout)在 System.Net.Mail.SmtpConnection.GetConnection(字符串主机，Int32 端口)在 System.Net.Mail.SmtpTransport System.Net.Mail.SmtpClient.GetConnection() 在 System.Net.Mail.SmtpClient.Send(MailMessage 消息)中的 .GetConnection(String host, Int32 port)

请您参考如下方法:

对于 SmtpException ，您总是必须通过 Exception.InnerException 检查内部异常属性(property)。总是。