Error while sending mail

Hi,

I have a ASPX which sends mails to users.
The code is :
try
{
     MailMessage mailMsg = new MailMessage();
     mailMsg.To = strToAddress;
     mailMsg.From = strFromAddress;
     mailMsg.Subject = strSubject;
     mailMsg.BodyFormat = MailFormat.Text;
     mailMsg.Body=strMessageBody;    
     SmtpMail.Send(mailMsg);
     return "Message was successfully sent.";
}
catch(Exception ex)
{
     return ex.InnerException + ex.StackTrace + ex.Message;
}
               
The stack trace is given below:
 
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.UnauthorizedAccessException: Access is denied. --- End of inner exception stack trace --- at System.RuntimeType.InvokeDispMethod(String name, BindingFlags invokeAttr, Object target, Object[] args, Boolean[] byrefModifiers, Int32 culture, String[] namedParameters) at System.RuntimeType.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParameters) at System.Web.Mail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) at System.Web.Mail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) at System.Web.Mail.CdoSysHelper.Send(MailMessage message) at System.Web.Mail.SmtpMail.Send(MailMessage message) at WWSFE.Util.SendEmail(String strToAddress, String strFromAddress, String strSubject, String strMessageBody) in c:\inetpub\wwwroot\wws\classfile\wwsfe.cs:line 2274Could not access 'CDO.Message' object.
 
How to overcome this problem.

Thanks in advance,
Nirmala S.