c# - vs2003 localhost から送信する smtpmailer が失敗することがある

Question

私は最も奇妙な問題を抱えています。ユーザーが複数のソースにメールを送信できるようにする VS2003 アプリケーションがあります。アプリケーションは動作しますが、アプリケーションからのメールが時々しか送信されないようです。テスト環境ではメールは毎回送信されますが、本番環境では時々失敗しますが、後でユーザーがメールを送信しようとすると成功します。誰でもこの理由を提案できますか?サーバー設定に問題があるのではないかと思いますが、それが何であるかはわかりません. 発生したエラーは以下です。

Server Error in '/PurchasingDept/rfqapp4' Application.

At least one recipient is required, but none were found.

Description: An unhandled exception occurred during the execution of the current web     request. Please review the stack trace for more information about the error and where it     originated in the code. 

Exception Details: System.Runtime.InteropServices.COMException: At least one recipient is required, but none were found. 

Source Error: 


Line 248:               ucDlgBox.ShowError("Mail failed!",
Line 249:                   "The Rfq mail has not been sent.<br>" +
Line 250:                   "Please contact the <a href='mailto:webmaster@guysuco.com'>" +
Line 251:                   "webmaster</a> referring to quote number " + gstrRFQNo + ".");
Line 252:       }

Source File: \\webtest\sites\intranet\purchasingdept\rfqapp4\managerfq\view.aspx.cs        Line: 250 

Stack Trace: 


[COMException (0x8004020c): At least one recipient is required, but none were found.
]

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeType.InvokeDispMethod(String name, BindingFlags invokeAttr, Object     target, Object[] args, Boolean[] byrefModifiers, Int32 culture, String[] namedParameters) +0
   System.RuntimeType.InvokeMember(String name, BindingFlags invokeAttr, Binder binder,     Object target, Object[] args, ParameterModifier[] modifiers, CultureInfo culture, String[]     namedParameters) +468
   System.Web.Mail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) +58

[HttpException (0x80004005): Could not access 'CDO.Message' object.]
   System.Web.Mail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) +112
   System.Web.Mail.CdoSysHelper.Send(MailMessage message) +1565
   System.Web.Mail.SmtpMail.Send(MailMessage message) +150
   Guysuco.RFQApp.Upgrade.MailRFQ.MailRFQToVendors2(String strFile, DataTable dtVendors) in e:\projects\guysuco.rfqapp.upgrade\mailrfq.cs:94
   Guysuco.RFQApp.Upgrade.MailRFQ.MailRFQ2(String RfqNoticeFile, String username, DateTime timeStamp) in e:\projects\guysuco.rfqapp.upgrade\mailrfq.cs:45
   Guysuco.RfqApp.managerfq.view.btnSend_Click(Object sender, EventArgs e) in     \\webtest\sites\intranet\purchasingdept\rfqapp4\managerfq\view.aspx.cs:250
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +108
     System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +57
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +18
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33
   System.Web.UI.Page.ProcessRequestMain() +1292