/// <summary>
        /// Download email messages from the POP3 server for a given Foe message processor.
        /// </summary>
        /// <param name="server">POP3 server information</param>
        /// <param name="processorEmail">The current Foe message processor's email address.</param>
        public static void DownloadMessages(PopServer server, string processorEmail)
        {
            // connect to POP3 server and download messages
            //FoeDebug.Print("Connecting to POP3 server...");
            POPClient popClient = new POPClient();

            popClient.IsUsingSsl = server.SslEnabled;

            popClient.Disconnect();
            popClient.Connect(server.ServerName, server.Port);
            popClient.Authenticate(server.UserName, server.Password);

            FoeDebug.Print("Connected to POP3.");

            // get mail count
            int count = popClient.GetMessageCount();

            FoeDebug.Print("Server reported " + count.ToString() + " messages.");

            // go through each message, from newest to oldest
            for (int i = count; i >= 1; i -= 1)
            {
                //FoeDebug.Print("Opening mail message...");

                OpenPOP.MIMEParser.Message msg = popClient.GetMessage(i, true);
                if (msg != null)
                {
                    // Get subject and verify sender identity
                    // Subject line in the mail header should look like one of the followings:
                    //
                    // Normal request (for news feed and content):
                    //   Subject: Request <Request ID> by <User ID>
                    //
                    // Registration request:
                    //   Subject: Register <Request ID> by Newbie
                    //
                    // where:
                    // Request ID is the request ID generated by the Foe client
                    // User ID is the user's ID as assigned by the server

                    //FoeDebug.Print("Message is not null. Getting message details.");

                    string subject   = msg.Subject;
                    string fromEmail = msg.FromEmail;

                    //FoeDebug.Print("Subject: " + subject);
                    //FoeDebug.Print("From: " + fromEmail);

                    // parse subject line
                    string[] tokens = subject.Trim().Split(new char[] { ' ' });
                    if (tokens.Length == 4)
                    {
                        // check what type of request is it
                        string requestType = tokens[0].ToUpper();
                        string requestId   = tokens[1];
                        string userId      = tokens[3];

                        FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Message,
                                         "subject: " + subject + "requestType: " + requestType);
                        if (requestType.ToUpper().CompareTo("REGISTE") == 0)
                        {
                            //FoeDebug.Print("This is a registration message.");
                            // It's a registration request
                            SaveRegistrationRequest(requestId, fromEmail, processorEmail);

                            FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Message,
                                             "Received registration request from " + fromEmail);
                        }
                        else if (requestType.ToUpper().CompareTo("CATALOG") == 0)
                        {
                            // get user info by email address
                            FoeUser user = FoeServerUser.GetUser(fromEmail);

                            // verify user's email against the user ID
                            if ((user != null) && (userId == user.UserId) && (processorEmail == user.ProcessorEmail))
                            {
                                FoeDebug.Print("User verified.");

                                // the user's identity is verified
                                SaveCatalogRequest(requestId, user.Email, processorEmail);
                            }
                            else
                            {
                                //FoeDebug.Print("User is not registered. Request not processed.");
                                FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Warning,
                                                 "Received content request from unregistered user " + fromEmail);
                            }
                        }
                        else if (requestType.ToUpper().CompareTo("CONTENT") == 0)
                        {
                            //FoeDebug.Print("This is a content request message.");

                            // It's a content request.
                            // We need to verify the user's identify first.

                            //FoeDebug.Print("Verifying user identity...");

                            // get user info by email address
                            FoeUser user = FoeServerUser.GetUser(fromEmail);

                            // verify user's email against the user ID
                            if ((user != null) && (userId == user.UserId) && (processorEmail == user.ProcessorEmail))
                            {
                                FoeDebug.Print("User verified.");

                                // the user's identity is verified
                                // get the full message body
                                OpenPOP.MIMEParser.Message wholeMsg = popClient.GetMessage(i, false);
                                string msgBody = (string)wholeMsg.MessageBody[0];

                                try
                                {
                                    // decompress it
                                    byte[] compressedMsg   = Convert.FromBase64String(msgBody);
                                    byte[] decompressedMsg = CompressionManager.Decompress(compressedMsg);
                                    string foe             = Encoding.UTF8.GetString(decompressedMsg);

                                    string[] catalogs = foe.Trim().Split(new char[] { ',' });
                                    // save request
                                    if (catalogs.Length == 0)
                                    {
                                        return;
                                    }
                                    SaveContentRequest(requestId, user.Email, catalogs, processorEmail);

                                    //FoeDebug.Print("Request saved and pending processing.");
                                    FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Message,
                                                     "Received content request from verified user " + fromEmail);
                                }
                                catch (Exception except)
                                {
                                    // the message is likely malformed
                                    // so just ignore it
                                    FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Warning,
                                                     "Received malformed content request from verified user " + fromEmail + "\r\n" +
                                                     except.ToString() +
                                                     "Raw message:\r\n" + msgBody + "\r\n");

                                    //throw except;
                                }
                            }
                            else
                            {
                                //FoeDebug.Print("User is not registered. Request not processed.");
                                FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Warning,
                                                 "Received content request from unregistered user " + fromEmail);
                            }
                        }
                        else if (requestType.ToUpper().CompareTo("FEED") == 0)
                        {
                            //FoeDebug.Print("This is a content request message.");

                            // It's a content request.
                            // We need to verify the user's identify first.

                            //FoeDebug.Print("Verifying user identity...");

                            // get user info by email address
                            FoeUser user = FoeServerUser.GetUser(fromEmail);

                            // verify user's email against the user ID
                            if ((user != null) && (userId == user.UserId) && (processorEmail == user.ProcessorEmail))
                            {
                                FoeDebug.Print("User verified.");

                                // the user's identity is verified
                                // get the full message body
                                OpenPOP.MIMEParser.Message wholeMsg = popClient.GetMessage(i, false);
                                string msgBody = (string)wholeMsg.MessageBody[0];

                                try
                                {
                                    // decompress it
                                    byte[] compressedMsg   = Convert.FromBase64String(msgBody);
                                    byte[] decompressedMsg = CompressionManager.Decompress(compressedMsg);
                                    string foe             = Encoding.UTF8.GetString(decompressedMsg);

                                    string[] array = foe.Trim().Split(new char[] { ',' });
                                    // save request
                                    if (array.Length == 0)
                                    {
                                        return;
                                    }
                                    SaveFeedRequest(requestId, user.Email, array, processorEmail);

                                    //FoeDebug.Print("Request saved and pending processing.");
                                    FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Message,
                                                     "Received feed request from verified user " + fromEmail);
                                }
                                catch (Exception except)
                                {
                                    // the message is likely malformed
                                    // so just ignore it
                                    FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Warning,
                                                     "Received malformed feed request from verified user " + fromEmail + "\r\n" +
                                                     except.ToString() +
                                                     "Raw message:\r\n" + msgBody + "\r\n");

                                    //throw except;
                                }
                            }
                            else
                            {
                                //FoeDebug.Print("User is not registered. Request not processed.");
                                FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Warning,
                                                 "Received content request from unregistered user " + fromEmail);
                            }
                        }
                        else
                        {
                            // Non-Foe message
                            FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Message,
                                             "Received non-Foe message from " + fromEmail);
                        }
                    }
                    else
                    {
                        // Non-Foe message
                        FoeServerLog.Add(_className + ".DownloadMessages", FoeServerLog.LogType.Message,
                                         "Received non-Foe message from " + fromEmail);
                    }

                    // Delete the current message
                    popClient.DeleteMessage(i);
                }
            }
            popClient.Disconnect();
        }
        public static void SendRssCache(string catalogCode, string userEmail, string requestId, bool isAutoSubscription)
        {
            // Load RSS
            string rss = FoeServerCatalog.GetRssCache(catalogCode);

            if (rss == null)
            {
                throw new Exception("RSS feed " + catalogCode + " does not exist.");
            }

            // Load User info
            FoeUser user = FoeServerUser.GetUser(userEmail);

            if (user == null)
            {
                throw new Exception("User " + userEmail + " does not exist.");
            }

            // Prepare Foe Message

            /*
             * string rssBase64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(feed.Rss));
             * FoeMessage foeMessage = new FoeMessage();
             * foeMessage.Add(new FoeMessageItem("CatalogCode", feed.Code));
             * foeMessage.Add(new FoeMessageItem("Rss", rssBase64));
             */

            FoeDebug.Print("Generated Foe Message.");

            // Send reply to user
            try
            {
                FoeServerMessage.SendMessage(
                    FoeServerMessage.GetDefaultSmtpServer(),
                    FoeServerRegistry.Get("ProcessorEmail"),
                    userEmail,
                    SubjectGenerator.ReplySubject(RequestType.Content, catalogCode, requestId, FoeServerUser.GetUser(userEmail).UserId),
                    rss);

                FoeDebug.Print("Sent reply to user.");

                // Add user to auto-subscription list
                if (!isAutoSubscription)
                {
                    FoeServerAutoSubscribe.Add(userEmail, catalogCode, requestId);
                }
                else
                {
                    // If the caller function is just processing AutoSubscription, then
                    // we don't want to recreate the subscription, simply update the
                    // current subscription.
                    FoeServerAutoSubscribe.Update(userEmail, catalogCode, requestId);
                }

                FoeDebug.Print("Added user to Auto Subscription.");
            }
            catch (Exception except)
            {
                FoeDebug.Print("FoeServerCatalog: Error sending email.");
                FoeDebug.Print(except.ToString());
            }
        }