diff --git a/README.md b/README.md
index 76f0203..ae9ef27 100644
--- a/README.md
+++ b/README.md
@@ -47,13 +47,20 @@ sudo mkdir -p /usr/local/inspamity
 # Clone the repository (or copy your files)
 sudo git clone https://github.com/dtump/inspamity.git /usr/local/inspamity
 
-# Set proper permissions
-sudo chmod +x /usr/local/inspamity/email_ai_interface.py
-sudo chmod +x /usr/local/inspamity/cli_toolbox.py
+# Set executable permissions
+sudo chmod 0755 /usr/local/inspamity/email_ai_interface.py
+sudo chmod 0755 /usr/local/inspamity/cli_toolbox.py
 
 # Create a virtual environment and install dependencies
 sudo python3 -m venv /usr/local/inspamity/.venv
 sudo /usr/local/inspamity/.venv/bin/pip install /usr/local/inspamity
+
+# Create system config and private debug locations
+sudo install -d -o root -g _rspamd -m 0750 /etc/inspamity
+sudo install -d -o _rspamd -g _rspamd -m 0700 /var/local/inspamity
+sudo cp /usr/local/inspamity/config.ini.default /etc/inspamity/config.ini
+sudo chown root:_rspamd /etc/inspamity/config.ini
+sudo chmod 0640 /etc/inspamity/config.ini
 ```
 
 ### Step 2: Install the rspamd integration
@@ -65,7 +72,8 @@ sudo cp /usr/local/inspamity/rspamd/external_ai_test.lua /etc/rspamd/plugins.d/
 # Create /etc/rspamd/modules.d/external_ai_test.conf
 echo -e 'external_ai_test {\n   enabled = true;\n}' | sudo tee /etc/rspamd/modules.d/external_ai_test.conf
 
-# Restart rspamd to apply changes
+# Verify rspamd config, then restart rspamd to apply changes
+sudo rspamadm configtest
 sudo systemctl restart rspamd
 ```
 
@@ -81,24 +89,32 @@ sudo tail -f /var/log/rspamd/rspamd.log
 
 ### Step 4: Enable debugging
 
-```bash
-# Make directory for debugging data
-mkdir /var/local/inspamity
+Debug mode can save raw email, processed email, AI output, and error logs. Treat these files as private mail data.
 
-# Make _rspamd owner of this directory
-chown _rspamd: /var/local/inspamity
+```bash
+# The installation step above creates this directory; these commands are safe to re-run.
+sudo install -d -o _rspamd -g _rspamd -m 0700 /var/local/inspamity
 ```
 
-After this, enable debugging in the config.ini
+After this, set `debug_mode = true` in `/etc/inspamity/config.ini` if you really need debug artifacts. Inspamity creates new debug files with mode `0600`.
 
 ## ⚙️ Configuration
 
-Copy `config.ini.default` to `config.ini` (or `/etc/inspamity/config.ini` for system-wide) and edit it:
+Copy `config.ini.default` to `/etc/inspamity/config.ini` for system-wide production use and edit it. Keep it readable only by root and the rspamd runtime user because it contains provider API keys:
+
+```bash
+sudo chown root:_rspamd /etc/inspamity/config.ini
+sudo chmod 0640 /etc/inspamity/config.ini
+sudo -u _rspamd test -r /etc/inspamity/config.ini
+```
 
 ```ini
 [settings]
 # AI provider: anthropic or openai
 provider = anthropic
+# Save private debug artifacts under debug_directory when true
+debug_mode = false
+debug_directory = /var/local/inspamity
 
 [anthropic]
 api_key = your_api_key_here
@@ -130,7 +146,7 @@ By default, the rspamd Lua script is configured to:
 - Apply a score based on the AI's confidence level
 - Log detailed information for debugging
 
-You can adjust these settings by editing `/etc/rspamd/local.d/external_ai_test.lua` to fit your needs.
+You can adjust these settings by editing the installed plugin at `/etc/rspamd/plugins.d/external_ai_test.lua` to fit your needs.
 
 ## 📊 How It Works
 
@@ -144,7 +160,10 @@ You can adjust these settings by editing `/etc/rspamd/local.d/external_ai_test.l
 
 - Check rspamd logs for errors: `sudo tail -f /var/log/rspamd/rspamd.log`
 - Test email processing directly: `/usr/local/inspamity/.venv/bin/python3 /usr/local/inspamity/email_ai_interface.py email.eml`
-- Verify permissions on all scripts and directories
+- Verify permissions on all scripts and directories:
+  - `/etc/inspamity` should be `0750 root:_rspamd`
+  - `/etc/inspamity/config.ini` should be `0640 root:_rspamd`
+  - `/var/local/inspamity` should be `0700 _rspamd:_rspamd`
 - Ensure all dependencies are properly installed
 
 ## 📜 License
diff --git a/config.ini.default b/config.ini.default
index 4e1be1a..581f200 100644
--- a/config.ini.default
+++ b/config.ini.default
@@ -1,9 +1,14 @@
+# Production config is normally /etc/inspamity/config.ini.
+# Recommended permissions: /etc/inspamity 0750 root:_rspamd, config.ini 0640 root:_rspamd.
+
 [settings]
 # AI provider to use: anthropic or openai
 provider = anthropic
 # Enable debug mode to save copies of processed emails and AI output
 debug_mode = false
-# Directory where debug files will be stored
+# Directory where debug files will be stored.
+# Treat this as private mail data; recommended permissions: 0700 _rspamd:_rspamd.
+# New debug files are created with mode 0600.
 debug_directory = /var/local/inspamity
 
 [anthropic]
diff --git a/email_ai_interface.py b/email_ai_interface.py
index 86510a3..16630bc 100755
--- a/email_ai_interface.py
+++ b/email_ai_interface.py
@@ -1,14 +1,55 @@
 #!/usr/bin/env python3
 import json
+import os
 import sys
 import traceback
 from datetime import datetime
 from pathlib import Path
+from typing import Any
 
 from email_utils.ai_spam_check import check_spam_with_ai
 from email_utils.config import load_config
 from email_utils.process_email import format_email_content, get_email_content
 
+DEBUG_DIR_MODE = 0o700
+DEBUG_FILE_MODE = 0o600
+
+
+def prepare_debug_directory(debug_dir: str) -> Path:
+    """Create and lock down the debug directory for private mail artifacts."""
+    debug_path = Path(debug_dir)
+    debug_path.mkdir(parents=True, mode=DEBUG_DIR_MODE, exist_ok=True)
+    debug_path.chmod(DEBUG_DIR_MODE)
+    return debug_path
+
+
+def write_private_text(path: Path, content: str) -> None:
+    """Write a debug text file without allowing group/other access."""
+    flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC
+    fd = os.open(path, flags, DEBUG_FILE_MODE)
+    try:
+        with os.fdopen(fd, "w", encoding="utf-8") as f:
+            fd = -1
+            f.write(content)
+    finally:
+        if fd != -1:
+            os.close(fd)
+        path.chmod(DEBUG_FILE_MODE)
+
+
+def write_private_json(path: Path, payload: dict[str, Any]) -> None:
+    """Write a debug JSON file without allowing group/other access."""
+    flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC
+    fd = os.open(path, flags, DEBUG_FILE_MODE)
+    try:
+        with os.fdopen(fd, "w", encoding="utf-8") as f:
+            fd = -1
+            json.dump(payload, f, indent=2)
+    finally:
+        if fd != -1:
+            os.close(fd)
+        path.chmod(DEBUG_FILE_MODE)
+
 
 def main() -> None:
     try:
@@ -32,12 +73,10 @@ def main() -> None:
             raise ValueError("Empty email input received")
 
         if debug_mode:
-            debug_path = Path(debug_dir)
-            debug_path.mkdir(parents=True, exist_ok=True)
+            debug_path = prepare_debug_directory(debug_dir)
             timestamp = datetime.now().strftime("%Y%m%d_%H%M%S_%f")
 
-            with open(debug_path / f"raw_email_{timestamp}.eml", "w", encoding="utf-8") as f:
-                f.write(email_content)
+            write_private_text(debug_path / f"raw_email_{timestamp}.eml", email_content)
 
         # Process the email
         processed_email = get_email_content(email_content, is_string=True)
@@ -47,11 +86,8 @@ def main() -> None:
         ai_result = check_spam_with_ai(formatted_output)
 
         if debug_mode:
-            with open(debug_path / f"processed_email_{timestamp}.txt", "w", encoding="utf-8") as f:
-                f.write(formatted_output)
-
-            with open(debug_path / f"ai_output_{timestamp}.json", "w", encoding="utf-8") as f:
-                json.dump(ai_result, f, indent=2)
+            write_private_text(debug_path / f"processed_email_{timestamp}.txt", formatted_output)
+            write_private_json(debug_path / f"ai_output_{timestamp}.json", ai_result)
 
         print(json.dumps(ai_result))
         sys.exit(0)
@@ -59,9 +95,10 @@ def main() -> None:
     except Exception as e:
         if "debug_mode" in locals() and debug_mode and "debug_path" in locals():
             error_timestamp = datetime.now().strftime("%Y%m%d_%H%M%S_%f")
-            with open(debug_path / f"error_{error_timestamp}.log", "w", encoding="utf-8") as f:
-                f.write(f"Error: {e}\n\n")
-                f.write(traceback.format_exc())
+            write_private_text(
+                debug_path / f"error_{error_timestamp}.log",
+                f"Error: {e}\n\n{traceback.format_exc()}",
+            )
 
         error_json = {"error": True, "message": str(e), "timestamp": datetime.now().isoformat()}
         print(json.dumps(error_json), file=sys.stderr)
diff --git a/tests/test_email_ai_interface.py b/tests/test_email_ai_interface.py
new file mode 100644
index 0000000..6b10e06
--- /dev/null
+++ b/tests/test_email_ai_interface.py
@@ -0,0 +1,44 @@
+import json
+import stat
+
+from email_ai_interface import prepare_debug_directory, write_private_json, write_private_text
+
+
+def mode(path):
+    return stat.S_IMODE(path.stat().st_mode)
+
+
+def test_prepare_debug_directory_uses_private_mode(tmp_path):
+    debug_dir = tmp_path / "debug"
+
+    prepare_debug_directory(str(debug_dir))
+
+    assert mode(debug_dir) == 0o700
+
+
+def test_prepare_debug_directory_tightens_existing_mode(tmp_path):
+    debug_dir = tmp_path / "debug"
+    debug_dir.mkdir(mode=0o755)
+
+    prepare_debug_directory(str(debug_dir))
+
+    assert mode(debug_dir) == 0o700
+
+
+def test_write_private_text_uses_private_mode(tmp_path):
+    debug_file = tmp_path / "raw_email_test.eml"
+
+    write_private_text(debug_file, "private mail")
+
+    assert debug_file.read_text() == "private mail"
+    assert mode(debug_file) == 0o600
+
+
+def test_write_private_json_uses_private_mode(tmp_path):
+    debug_file = tmp_path / "ai_output_test.json"
+    payload = {"is_spam": "no", "confidence": 99, "reason": "test"}
+
+    write_private_json(debug_file, payload)
+
+    assert json.loads(debug_file.read_text()) == payload
+    assert mode(debug_file) == 0o600