Email Signature Manager

A self-hosted, Dockerized Google Workspace email signature manager. Runs as a single container — designed for Unraid but works on any Docker host. See INSTALL.md for Unraid-specific instructions.

Features

• Pulls user data automatically from Google Workspace Directory API
• Renders per-user HTML signatures via Handlebars templates
• Pushes signatures directly to Gmail via sendAs API (web + mobile)
• Nightly batch push via configurable cron schedule
• Web admin UI — live template editor with real-time preview
• Template Versioning — save multiple versions and recall them later
• Single-user push for testing and onboarding
• SQLite audit log of every push event
• Basic auth protected UI
• Zero external services — single container, no database server

---

Logo & Image Hosting

All images referenced in the signature template must be publicly accessible via HTTPS. The default logo URL is:

https://alwisp.com/uploads/logo.png

Upload your logo and any other signature images to https://alwisp.com/uploads/ and reference them by full URL in the template. The logo URL can also be changed live in the Template Editor UI without rebuilding the container.

---

Environment Variables

All secrets and configuration are passed as environment variables at runtime. No .env file is committed to this repo — see .env.example for all variable names.

Variable	Description	Default
GOOGLE_ADMIN_EMAIL	Workspace admin email (e.g. jason@messagepoint.tv)	(required)
GOOGLE_CUSTOMER_ID	Use my_customer for primary domain	my_customer
SERVICE_ACCOUNT_KEY_PATH	Path to sa.json inside container	/app/secrets/sa.json
ADMIN_USERNAME	Web UI login username	(required)
ADMIN_PASSWORD	Web UI login password	(required)
PORT	Internal app port	3000
CRON_SCHEDULE	Cron expression for nightly push	0 2 * * *
NODE_ENV	Node environment	production

On Unraid

Set each variable directly in the Docker container template UI under Variables.

For Local Development

cp .env.example .env
# fill in values
docker-compose --env-file .env up -d --build

---

Part 1 — Google Cloud Console Setup

Step 1 — Create a Google Cloud Project

1. Open https://console.cloud.google.com — sign in with your Google Workspace admin account
2. Click the project dropdown (top nav bar) → New Project
3. Name: email-sig-manager → Create
4. Select the new project from the dropdown to make it active

Step 2 — Enable Required APIs

Admin SDK API:

1. Go to APIs & Services → Library
2. Search Admin SDK API → click result → Enable

Gmail API:

1. Go back to APIs & Services → Library
2. Search Gmail API → click result → Enable

Step 3 — Create the Service Account

1. Go to IAM & Admin → Service Accounts
2. Click + Create Service Account
3. Name: email-sig-manager → Create and Continue
4. Skip role assignment → Continue → skip user access → Done

Step 4 — Enable Domain-Wide Delegation

1. Click the service account name to open it
2. Click Edit (pencil icon)
3. Expand Show advanced settings
4. Check Enable Google Workspace Domain-wide Delegation
5. Enter product name: Email Signature Manager
6. Click Save
7. Back on the service account detail page, note the Client ID (long number) — copy it

Step 5 — Download the JSON Key

1. Click the Keys tab on the service account
2. Add Key → Create New Key → JSON → Create
3. Rename the downloaded file to sa.json
4. Place it at secrets/sa.json on your Unraid host — never commit to GitHub

---

Part 2 — Google Admin Console Authorization

Step 6 — Authorize Domain-Wide Delegation

1. Go to https://admin.google.com — sign in as super admin
2. Navigate to: Security → Access and data control → API controls
3. Click Manage Domain Wide Delegation
4. Click Add new
5. Fill in:
   • Client ID: (paste the number from Step 4)
   • OAuth Scopes:

     https://www.googleapis.com/auth/admin.directory.user.readonly,https://www.googleapis.com/auth/gmail.settings.basic
     

6. Click Authorize

If you get "client ID not found" — wait 2–3 minutes after Step 4 and try again.

Step 7 — Verify

1. Click View details next to your new entry
2. Confirm both scopes are listed
3. If a scope is missing, click Edit, re-enter the full scope string, and re-authorize

---

Part 3 — Unraid Deployment

Step 8 — Clone the Repo

cd /mnt/user/appdata
git clone https://git.alwisp.com/jason/email.git email-sigs
cd email-sigs

Step 9 — Place the Service Account Key

# From your PC (run on your PC):
scp sa.json root@UNRAID-IP:/mnt/user/appdata/email-sigs/secrets/sa.json

Or copy via SMB: \\UNRAID-IP\appdata\email-sigs\secrets\

Step 10 — Upload Logo

Upload your logo to https://alwisp.com/uploads/logo.png via your web server. The template references this URL directly — no local file needed.

Step 11 — Build the Docker Image

SSH into Unraid and run:

cd /mnt/user/appdata/email-sigs
docker build -t email-sigs:latest .

Step 12 — Configure Container in Unraid Docker UI

• Name: email-sigs
• Repository: email-sigs (local image built in Step 11)

Volume mappings:

Host Path	Container Path
/mnt/user/appdata/email-sigs/secrets	/app/secrets
/mnt/user/appdata/email-sigs/data	/app/data
/mnt/user/appdata/email-sigs/public/assets	/app/public/assets

Port mapping: Host 3000 → Container 3000

Variables:

Name	Value
GOOGLE_ADMIN_EMAIL	jason@messagepoint.tv
GOOGLE_CUSTOMER_ID	my_customer
SERVICE_ACCOUNT_KEY_PATH	/app/secrets/sa.json
ADMIN_USERNAME	admin
ADMIN_PASSWORD	(your chosen password)
PORT	3000
CRON_SCHEDULE	0 2 * * *
NODE_ENV	production

---

Part 4 — First Run & Verification

Step 13 — Access the UI

http://UNRAID-IP:3000

Step 14 — Preview and Test

1. Go to Template Editor — verify the preview renders correctly
2. Back on Dashboard → enter your own email → Push Single User
3. Open Gmail → compose a new message → verify signature appears
4. Check Gmail mobile app (force-close and reopen if needed)

Step 15 — Push to All Users

Once verified, click Push to All Users on the Dashboard. The nightly cron will keep all signatures in sync automatically.

---

Updating

cd /mnt/user/appdata/email-sigs
git pull
docker build -t email-sigs:latest .
docker restart email-sigs

---

Project Structure

email-sig-manager/
├── src/
│   ├── index.js              # Express app (no dotenv — vars injected by Docker)
│   │   ├── admin.js          # Template, logs, users API
│   │   └── push.js           # Signature push logic + batch runner
│   ├── services/
│   │   ├── googleAdmin.js    # Directory API — fetch all users
│   │   ├── gmailApi.js       # Gmail sendAs patch
│   │   ├── renderer.js       # Handlebars template renderer
│   │   └── scheduler.js      # node-cron nightly job
│   └── db/
│       ├── sqlite.js         # DB init and connection
│       └── audit.js          # Audit log read/write
├── templates/
│   └── default.hbs           # 2-column HTML signature template
├── public/
│   ├── dashboard.html        # Admin dashboard UI
│   ├── editor.html           # Template editor with live preview
│   └── assets/               # Local asset dir (optional, logo served remotely)
├── secrets/                  # Gitignored — sa.json goes here
├── data/                     # Gitignored — SQLite DB lives here
├── Dockerfile                # Uses npm install (not npm ci)
├── docker-compose.yml
├── package.json
└── .env.example              # Variable reference — safe to commit

---

Cron Schedule Reference

Expression	Meaning
0 2 * * *	2:00 AM every day (default)
0 6 * * *	6:00 AM every day
0 2 * * 1	2:00 AM every Monday
0 2 1 * *	2:00 AM on the 1st of each month

---

Troubleshooting

"Cannot find module" errors on startup Rebuild the image: docker build -t email-sigs:latest . then restart.

Container won't start Run docker logs email-sigs — most likely a missing env variable or malformed sa.json.

"No primary sendAs" error The user may not have an active Gmail account, or domain-wide delegation scopes were not saved correctly.

"Client ID not found" in Google Admin Wait 2–3 minutes after enabling domain-wide delegation in GCP, then try again.

Signatures not showing on mobile Gmail iOS/Android uses the web signature automatically. Force-close and reopen the app.

Template changes not saving Verify the container has write access to templates/. A .bak file is created on every save.

401 / permission denied errors Go to Google Admin → Security → API Controls → Domain Wide Delegation → View Details and verify both OAuth scopes are listed correctly.

---

Security Notes

• sa.json grants impersonation rights to every user in your domain — treat it like a master key
• Never commit sa.json to GitHub — it is gitignored
• Change ADMIN_PASSWORD before first deployment
• Consider HTTPS via a reverse proxy if the UI is accessible outside your LAN