Set ServerSide ConfirmBox

SetAlert(btnSendEmailTest, "Are you sure you want to send this email")

Public Shared Sub SetAlert(ByVal ctrl As WebControl, ByVal Message As String)
 If (HttpContext.Current.Request.Browser.Type.ToUpper().IndexOf("IE") >= 0) Then
     ctrl.Attributes.Add("onclick", "event.returnValue=confirm('" & Message & "?');")  
 Else      
    ctrl.Attributes.Add("onclick", "return confirm('" & Message & "?');")  
 End If
End Sub

C#.Net
 
SetAlert(btnSendEmailTest, "Are you sure you want to send this email")public static void SetAlert(WebControl ctrl, String Message)
{
  if ((HttpContext.Current.Request.Browser.Type.ToUpper().IndexOf("IE") >= 0)) 
  {
    ctrl.Attributes.Add("onclick", ""event.returnValue=confirm('" + Message + "?');");
  }
  else
  {
    ctrl.Attributes.Add("onclick", "return confirm('" & Message & "?');");  } 
}