while(validLogin == false) {
                if (messageIn.toUpperCase().startsWith("CREATE")) {
                    FileWriter loginWriter = new FileWriter("LoginDetails.txt", true);


                    dataOut.writeUTF("Please enter a Username: ");
                    username = dataIn.readUTF();

                    dataOut.writeUTF("Please enter a Password: ");
                    password = dataIn.readUTF();

                    createBuffer.mark(10000);
                    while((currentLine = createBuffer.readLine()) != null) {
                        String[] subStrings = currentLine.split(":");
                        String usernameSub = subStrings[0];
                        String passwordSub = subStrings[1];

                        if (username.equals(subStrings[0])) {
                            dataOut.writeUTF("Login Already Exists, Try Logging In...");
                            username = dataIn.readUTF();

                        }
                        else {
                            if(username != null || username != " ") {
                                loginWriter.write(username + ":" + password + "\r\n");
                                dataOut.writeUTF("Login Created, Logging in now...");
                                loginWriter.close();
                                validLogin = true;
                                break;
                        }
                    }
                    createBuffer.reset();

                    if (validLogin == false) {
                        dataOut.writeUTF("Login Failed");
                        }
                    }
                }
                createBuffer.close();

                if (messageIn.toUpperCase().startsWith("LOGIN")){
                    BufferedReader loginBuffer = new BufferedReader(new FileReader("LoginDetails.txt"));

                    dataOut.writeUTF("Username: ");
                    username = dataIn.readUTF();

                    pattern = Pattern.compile(emailRegex);
                    matcher = pattern.matcher(username);
                    if(matcher.matches() == true){

                        dataOut.writeUTF("Password: ");
                        password = dataIn.readUTF();

                        loginBuffer.mark(10000);

                        while((currentLine = loginBuffer.readLine()) != null) {
                            String[] subStrings = currentLine.split(":");
                            String usernameSub = subStrings[0];
                            String passwordSub = subStrings[1];

                            if (username.equals(subStrings[0]) && password.equals(subStrings[1])) {
                                dataOut.writeUTF("Valid Login, Logging In...");
                                validLogin = true;
                                retrieving = true;
                                break;
                            }
                        }
                        loginBuffer.reset();

                        if(validLogin == false) {
                            dataOut.writeUTF("Login Failed");
                        }
                        loginBuffer.close();
                    }
                    else {
                        dataOut.writeUTF("Error in Logging In, Try Again");
                        messageIn = dataIn.readUTF();
                    }
                }
            }

            while(retrieving == true) {
                BufferedReader msgReader = new BufferedReader(new FileReader("SMTPMsgs.txt"));
                StringBuffer sb = new StringBuffer();

                while(true) {
                    String line = msgReader.readLine();
                    if (line == null) {
                        break;
                    }
                    sb.append(line).append("\n");
                }

                String[] messages = sb.toString().split("------END OF MESSAGE------");

                for (String message : messages) {
                    message = message.trim();
                    //message = individual message from file
                    String[] data = message.split("\n");
                    String sender = data[1];
                    sender.replace("FROM: ", "");

                    if (username.equals(sender)) {
                        for (String d : data) {
                            dataOut.writeUTF(d);
                        }
                        dataOut.writeUTF("\r\n");
                    }
                    else {
                        break;
                    }
                }
                retrieving = false;
                msgReader.close();
            }