C＃应用程序发送电子邮件。错误[发送邮件失败。]

Question

我正在Visual Studio 2012 RC中使用.NET Framework 4.5在C＃中构建应用程序。

我发送电子邮件到我的帐户的应用反馈和问题的缘故。 这是一个小应用程序。

前几天我的申请被运行良好。我正在收到电子邮件。

现在我有例外，因为弹出“发送邮件失败。”

我尝试了很多的调整，但没有效果。我的帐户不要求重新激活。我也关闭了防火墙。除此之外没有任何工作。我附上一个例外细节。太。 请看看它。

请帮帮我。我做了太多的谷歌。

我的代码是

MailMessage message = new MailMessage(); 
try 
{ 
    message.To.Add(new MailAddress(mailTo)); 
    message.From = new MailAddress(mailFrom); 

    //Attachment attachment = new Attachment(FileUpload1.PostedFile.FileName); 
    message.Subject = "McFarlane Industries Product's Registration Request"; 
    message.Body = packageRequestContent(); 
    message.BodyEncoding = System.Text.Encoding.UTF8; 
    message.SubjectEncoding = System.Text.Encoding.UTF8; 
    //message.Attachments.Add(attachment); 


    SmtpClient client = new SmtpClient(); 
    client.Port = 587; // Gmail works on this port 
    client.Host = "smtp.gmail.com"; 
    System.Net.NetworkCredential nc = new System.Net.NetworkCredential(mailFrom, mailFromPass); 
    client.EnableSsl = true; 
    client.UseDefaultCredentials = false; 
    client.Credentials = nc; 
    client.Send(message); 
    MessageBox.Show("Thank you for Registring...!", "Register Notification!", MessageBoxButtons.OK, MessageBoxIcon.Information); 


} 
catch (Exception ex) 
{ 
    MessageBox.Show("Request not submitted. " + ex.Message); 
} 

异常的详细信息是：

System.Net.Mail.SmtpException was unhandled 
    HResult=-2146233088 
    Message=Failure sending mail. 
    Source=System 
    StackTrace: 
     at System.Net.Mail.SmtpClient.Send(MailMessage message) 
     at McFarlaneIndustriesPOSnamespace.Registration.sendMailUsingHotmail(String mailFrom, String mailFromPass, String mailTo) in e:\Works\McFarlane Industries\McFarlane Industries Point of Sale Source Code\McFarlaneIndustries\Registration.cs:line 73 
     at McFarlaneIndustriesPOSnamespace.Registration.buttonSendRegistrationRequest_Click(Object sender, EventArgs e) in e:\Works\McFarlane Industries\McFarlane Industries Point of Sale Source Code\McFarlaneIndustries\Registration.cs:line 47 
     at System.Windows.Forms.Control.OnClick(EventArgs e) 
     at System.Windows.Forms.Button.OnClick(EventArgs e) 
     at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent) 
     at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) 
     at System.Windows.Forms.Control.WndProc(Message& m) 
     at System.Windows.Forms.ButtonBase.WndProc(Message& m) 
     at System.Windows.Forms.Button.WndProc(Message& m) 
     at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) 
     at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) 
     at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) 
     at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) 
     at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData) 
     at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) 
     at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) 
     at System.Windows.Forms.Application.Run(Form mainForm) 
     at McFarlaneIndustriesPOSnamespace.Program.Main() in e:\Works\McFarlane Industries\McFarlane Industries Point of Sale Source Code\McFarlaneIndustries\Program.cs:line 20 
     at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) 
     at System.AppDomain.nExecuteAssembly(RuntimeAssembly assembly, String[] args) 
     at System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel) 
     at System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly() 
     at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[] activationCustomData) 
     at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext) 
     at System.Activator.CreateInstance(ActivationContext activationContext) 
     at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone() 
     at System.Threading.ThreadHelper.ThreadStart_Context(Object state) 
     at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx) 
     at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx) 
     at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 
     at System.Threading.ThreadHelper.ThreadStart() 
    InnerException: System.IO.IOException 
     HResult=-2146232800 
     Message=Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. 
     Source=System 
     StackTrace: 
      at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size) 
      at System.Net.DelegatedStream.Read(Byte[] buffer, Int32 offset, Int32 count) 
      at System.Net.BufferedReadStream.Read(Byte[] buffer, Int32 offset, Int32 count) 
      at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine) 
      at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller) 
      at System.Net.Mail.CheckCommand.Send(SmtpConnection conn, String& response) 
      at System.Net.Mail.StartTlsCommand.Send(SmtpConnection conn) 
      at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint) 
      at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint) 
      at System.Net.Mail.SmtpClient.GetConnection() 
      at System.Net.Mail.SmtpClient.Send(MailMessage message) 
     InnerException: System.Net.Sockets.SocketException 
      HResult=-2147467259 
      Message=An existing connection was forcibly closed by the remote host 
      Source=System 
      ErrorCode=10054 
      NativeErrorCode=10054 
      StackTrace: 
       at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags) 
       at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size) 
      InnerException: 

Answer 1

我会尝试登录到使用Web界面的Hotmail/Gmail帐户。有时Hotmail会随机锁定您的帐户并重置密码;特别是如果您使用该帐户发送批量电子邮件。