Domain Email Signatures

Google Workspace has no bulk signature management. You can set a signature for one user at a time through Gmail settings — that's it. For a domain with hundreds of employees across multiple office locations, job titles, and phone numbers, that's not a workflow.

This toolkit manages email signatures at the domain level: define HTML templates, store each user's signature fields (title, location, phone, extension) in Google Directory's custom schema, and push rendered signatures to every user's Gmail account programmatically. When someone's phone number changes or a new template rolls out to a branch, one script run updates everyone.

Scripts

Script	Purpose
scripts/email_templates.py	Defines all HTML signature templates with dynamic field injection
scripts/authenticator.py	Google service account auth and API service builders
scripts/google_api.py	Shared helpers: bulk signature push, error reporting, user fetching
scripts/all_user_download.py	Downloads all user records from the Admin SDK to CSV
scripts/get_all_signatures.py	Exports every active user's live Gmail signature HTML to a shared Drive folder
scripts/update_sig_info.py	Patches multiple Signature_Info fields for a roster of users (dry-run by default)
scripts/update_sig_field.py	Bulk-sets a single field to the same value across a targeted user list
scripts/update_single.py	Updates the live signature for one user; generates a preview image
scripts/sig_info_report.py	Exports the Signature_Info custom schema for all users to CSV
scripts/audit_template.py	Audits which users have a specific template applied and flags mismatches
scripts/verify_template.py	Verifies a roster of users have the correct template and field values
scripts/preview_template.py	Renders a JPG preview for a roster of users without pushing to Gmail
scripts/check_team_template.py	Checks that all members of a group have a consistent template
scripts/push_phone_updates.py	Pushes phone number updates to a targeted user list
scripts/lookup_orgunits.py	Lists the org unit path for every user in the domain

Setup

Prerequisites

• Python 3.9+
• Google Cloud project with Gmail API and Admin SDK enabled
• Service account with domain-wide delegation and the following scopes:
  • https://www.googleapis.com/auth/admin.directory.user
  • https://www.googleapis.com/auth/admin.directory.userschema
  • https://www.googleapis.com/auth/gmail.settings.basic
  • https://www.googleapis.com/auth/gmail.settings.sharing
  • https://www.googleapis.com/auth/drive (for get_all_signatures.py)
• wkhtmltopdf installed and on PATH (for update_single.py preview images)

Installation

pip install -r requirements.txt

Configuration

Copy .env.example to .env and fill in your values:

cp .env.example .env

Place your service account key JSON in a Keys/ folder (or set KEY_PATH in .env to its absolute path). The authenticator.py module searches several common locations and also respects KEY_PATH as an override.

How It Works

1. Auth — A service account with domain-wide delegation impersonates the admin user to call the Admin SDK, then impersonates each individual user to call the Gmail API on their behalf.
2. Custom schema — Signature fields (title, location, extension, direct line, template key) are stored in a Signature_Info custom schema on each user's Google Directory profile. This makes them queryable and auditable without touching Gmail directly.
3. Pagination — The Admin SDK returns up to 500 users per page; scripts loop through all pages via nextPageToken.
4. Template selection — email_templates.py maps a Template key (e.g. branch_a, corp_hr) to a fully rendered HTML string. The key is stored in each user's Signature_Info schema and read at push time.
5. Application — Each user's signature is set via users.settings.sendAs.patch targeting their primary send-as address.
6. Dry-run safety — update_sig_info.py and update_sig_field.py default to dry-run mode and print diffs before writing. Pass --apply to commit changes.