diff --git a/README.md b/README.md
index 9042815..48954a9 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@
   <a href="#features">Features</a> •
   <a href="#requirements">Requirements</a> •
   <a href="#installation">Installation</a> •
-  <a href="#Configuration">Configuration</a> •
+  <a href="#configuration">Configuration</a> •
   <a href="#contributing">Contributing</a> •
   <a href="#license">License</a>
 </p>
@@ -22,12 +22,13 @@
 
 - 📄 Add **text** and **URL bookmarks** into your Karakeep instance (tested on [v0.25.0](https://github.com/karakeep-app/karakeep/releases/tag/v0.25.0)).
 - 🤖 Obtain **AI-generated tags** in **hashtag format** for easy searching on Telegram.
-- 🔒 Support **chat ID and thread ID allowlists**.
+- 🔒 **Mandatory chat ID allowlist** to prevent abuse (**thread ID allowlist** is also supported).
 - 🐳 **Production-ready Docker image** for easy **deployment**.
 
 ## Requirements
 
 - A [Telegram bot token](https://core.telegram.org/bots/features#botfather) (you can get one by talking to [@BotFather](https://t.me/BotFather) on Telegram)
+- Your Telegram Chat ID (see [How to Find Your Chat ID](#how-to-find-your-chat-id)).
 - A valid API key from [Karakeep](https://docs.karakeep.app/screenshots#settings).
 
 ## Installation
@@ -41,6 +42,7 @@ Use the `docker run` command to start `Karakeepbot`. Make sure to set the requir
 ```sh
 docker run --name karakeepbot \
   -e KARAKEEPBOT_TELEGRAM_TOKEN=your-telegram-bot-token \
+  -e KARAKEEPBOT_TELEGRAM_ALLOWLIST=your-telegram-chat-id \
   -e KARAKEEPBOT_KARAKEEP_TOKEN=your-karakeep-api-key \
   -e KARAKEEPBOT_KARAKEEP_URL=https://your-karakeep-instance.tld \
   ghcr.io/madh93/karakeepbot:latest
@@ -59,6 +61,7 @@ services:
     #   - ./custom.config.toml:/var/run/ko/config.default.toml # Optional: specify a custom configuration file instead of the default one
     environment:
       - KARAKEEPBOT_TELEGRAM_TOKEN=your-telegram-bot-token
+      - KARAKEEPBOT_TELEGRAM_ALLOWLIST=your-telegram-chat-id
       - KARAKEEPBOT_KARAKEEP_TOKEN=your-karakeep-api-key
       - KARAKEEPBOT_KARAKEEP_URL=https://your-karakeep-instance.tld
 ```
@@ -95,7 +98,7 @@ go install github.com/Madh93/karakeepbot@latest
 You can load a different configuration file by using the `-config path/to/config/file` flag when starting the application:
 
 ```sh
-karakeepbot -config custom.config.tml
+karakeepbot -config custom.config.toml
 ```
 
 ### Overriding with environment variables
@@ -106,6 +109,21 @@ Additionally, you can override the configuration values using environment variab
 KARAKEEPBOT_LOGGING_LEVEL=debug KARAKEEPBOT_TELEGRAM_ALLOWLIST=chat_id_1,chat_id_2 karakeepbot
 ```
 
+### Security Concerns
+
+To protect your bot from abuse and spam from unauthorized users, `Karakeepbot` implements a **mandatory Chat ID allowlist**.
+
+By default, the bot is configured with a placeholder value and **it will not start** until you explicitly configure the `telegram.allowlist` parameter. You have two options:
+
+1. **Recommended:** Provide a list of one or more specific Chat IDs. This ensures only you and other authorized users can interact with the bot.
+2. **Not Recommended:** Provide an empty list (`[]`). This will allow any Telegram user to interact with your bot, exposing it to potential abuse.
+
+#### How to Find Your Chat ID
+
+1. Open your Telegram client.
+2. Search for the bot `@userinfobot` and start a chat with it.
+3. The bot will immediately reply with your user information, including your **Id**. This is your Chat ID.
+
 ## Contributing
 
 Contributions are welcome! Please open an issue or submit a pull request for any bug fixes or enhancements.
diff --git a/config.default.toml b/config.default.toml
index b4f4064..6ca1e25 100644
--- a/config.default.toml
+++ b/config.default.toml
@@ -8,9 +8,11 @@
 # Telegram bot token
 token = "<YOUR_BOT_TOKEN_FROM_BOTFATHER>"
 
-# Allowed chat IDs for the bot to interact with. If empty (default), the bot
-# will interact with all chats.
-allowlist = []
+# Allowed chat IDs for the bot to interact with. It is strongly recommended to
+# set this to your personal chat ID to prevent abuse. The bot will not start
+# with the default value. You can get your chat ID by talking to @userinfobot on
+# Telegram. If empty, the bot will interact with all chats.
+allowlist = [-1]
 
 # Allowed thread IDs (a.k.a topics) for the bot to interact with. If empty
 # (default), the bot will interact with all threads.
diff --git a/internal/config/config.go b/internal/config/config.go
index 0bb439a..bd2ba04 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -67,7 +67,7 @@ var DefaultPath = filepath.Join(os.Getenv("KO_DATA_PATH"), DefaultConfigFile)
 // DefaultConfig is the default configuration for the bot.
 var DefaultConfig = Config{
 	Telegram: TelegramConfig{
-		Allowlist: []int64(nil),
+		Allowlist: []int64{-1}, // Enforce allowlist by default.
 		Threads:   []int(nil),
 	},
 	Karakeep: KarakeepConfig{
@@ -159,8 +159,7 @@ func parseCommandLineFlags(config *Config) {
 // validateConfig checks the validity of the configuration.
 func validateConfig(config *Config) error {
 	if err := config.Telegram.Validate(); err != nil {
-		log.Printf("WRN: %v", err) // Telegram Bot Token validation couldn't be be 100% reliable.
-		return nil
+		return err
 	}
 	if err := config.Karakeep.Validate(); err != nil {
 		return err
diff --git a/internal/config/telegram.go b/internal/config/telegram.go
index 9033c19..5f7bf60 100644
--- a/internal/config/telegram.go
+++ b/internal/config/telegram.go
@@ -1,6 +1,8 @@
 package config
 
 import (
+	"fmt"
+
 	"github.com/Madh93/karakeepbot/internal/secret"
 	"github.com/Madh93/karakeepbot/internal/validation"
 )
@@ -18,5 +20,9 @@ func (c TelegramConfig) Validate() error {
 		return err
 	}
 
+	if len(c.Allowlist) == 1 && c.Allowlist[0] == -1 {
+		return fmt.Errorf("invalid Telegram Allowlist (-1). Please configure it with your actual chat ID or an empty list to allow all users (not recommended)")
+	}
+
 	return nil
 }