Open-source · self-hosted · Microsoft 365

Own your Outlook signatures.

Give Communications a real publishing workspace. Give IT control of identity and access. Give every employee the right signature—automatically.

Get the source Read the deployment guide

One containerNode + SQLite
Your tenantYour directory data
Every OutlookModern, classic & mobile

Signature operations

Cornerstone Signatures administration dashboard showing managed staff, deployments, audit activity, and Outlook client analytics

96% covered27 of 28 staff

12,847managed signatures delivered

01Keep control

Run it in your own environment and keep directory, template, and audit data on your infrastructure.

02Split responsibilities

IT governs people and policy. Communications designs and publishes without waiting on a ticket.

03Automate the last mile

The Outlook add-in selects and inserts the right published signature while a message is composed.

A complete operating model

Not a signature generator.
A signature management system.

Everything between Microsoft Entra and a finished Outlook message lives in one controlled workflow.

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Automatic Outlook delivery

Event-based activation inserts the current managed signature on compose and responds to supported From-address changes. The task pane previews and reapplies on demand.

WebNew WindowsClassic WindowsmacOSiOSAndroid

✦

Visual or direct HTML

Build responsive signatures in the MJML visual editor, or keep precise control with tested email-safe HTML.

◎

Audience priority

Publish a default for everyone, then let higher-priority limited audiences override it without duplicating staff data.

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Entra synchronization

Sync staff, shared mailboxes, profile photos, titles, locations, and phones. Filter imports and preserve local overrides.

◌

Controlled self-service

Let selected users opt out, choose approved taglines, and add admin-defined professional designations.

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Audit, analytics & backup

Track administrative changes, client and version adoption, alternate-From usage, and complete database exports.

◴

Scheduled publishing

Prepare campaign changes in advance, schedule immutable revisions, cancel pending releases, and preserve history.

The product, not a mock-up

Built for the people
who actually operate it.

These screens come from a local installation populated exclusively with fictional demonstration data.

IT workspace

See the whole system at a glance.

Coverage, publishing status, audit activity, client adoption, and shared-mailbox usage are visible without assembling reports from separate systems.

Live delivery counts
Client family and version breakdown
Primary vs. alternate From analytics

Dashboard

Staff & access

Staff and access table with directory information, eligibility, visibility, roles, preview, and management actions

Directory control

Make imperfect directory data usable.

Entra stays authoritative while IT retains safe, local control over the fields and permissions that affect signatures.

Scheduled and filtered sync
Bulk applicability and visibility
Title, location, and phone overrides
Shared-mailbox identity modes

Communications workspace

Design, approve, and publish without a deployment.

Draft changes stay drafts. Publishing creates an immutable revision, while live directory data and safe merge tags remain current.

Visual MJML and legacy HTML
Preview as any managed user
Duplicate, version, schedule, publish

Signature templates

Signature template cards with visual and HTML template types, previews, versions, and publishing actions

Deployment workspace with scheduled and active signature releases

Controlled deploymentsSchedule, prioritize, publish, and roll back.

Reusable limited audiences and member counts

Reusable audiencesTarget once, publish repeatedly.

Approved languageTaglines managed by Communications.

Organization information and location mapping settings

Configuration that belongs in the appOrganization data, mappings, defaults, and more.

Readable administrative audit log with export controls

Traceable operationsEvery meaningful administrative change, ready to export.

A better front door

Employees see only what they need.

The staff-facing page explains automatic delivery, previews the published signature, and exposes only the preferences IT has enabled for that person.

Optional opt-outApproved tagline choiceProfessional designationsCopy for unsupported clients

Managed signature

Small operational footprint

Serious controls.
Refreshingly little infrastructure.

One container serves the staff page, administration workspace, Outlook runtime, signature API, and in-process schedulers. One SQLite database on a persistent volume stores managed state.

Explore the deployment architecture

Microsoft EntraIT administratorsCommunications

Cornerstone
SignaturesNode 24 container

SQLite volumeOutlook clients

Docker / OCISQLiteMicrosoft GraphOffice.jsMJMLCloudflare Access

No per-user tax

Make signatures infrastructure,
not another subscription.

Deploy it, shape it around your organization, and keep the source available to the people who depend on it.

View the repository Read the user guide