EmailEngine Email API
A headless email client application that provides access to IMAP, SMTP, Gmail API, and MS Graph API resources via a unified REST API. Easily integrate email accounts with your service!
[!WARNING]
EmailEngine is not free open-source software. It is "source available" software, meaning you can view and copy the source code, but you need a paid subscription to run it beyond the free 14-day trial. Each EmailEngine instance comes with this trial, so you can test EmailEngine without any commitment.
Use Cases
- Sync users' emails with your service and send emails on their behalf.
- Integrate your app with a dedicated email account, such as your support email.
- Monitor INBOX and Junk folders of a test email account to track where sent emails land.
- Ideal for lightweight webmail and mobile email apps that prefer to avoid direct IMAP and MIME processing.
Features
- One REST API for every provider. IMAP/SMTP, the Gmail API, and Microsoft Graph are all exposed through the same endpoints, so your integration does not change when a user switches provider.
- Real-time webhooks. Get notified about new, deleted, and updated messages, sent mail, delivery errors, bounces, and account state changes. Optional custom routes filter and reshape payloads per destination.
- Sending. Queued delivery with retries, stored templates, sending gateways, open and click tracking, unsubscribe handling, a blocklist, and bounce classification.
- Account onboarding. A hosted authentication form handles OAuth2 (Google, Microsoft) and IMAP credentials so you never touch the user's password.
- Bulk export. Export an account's mail to compressed NDJSON, optionally encrypted.
- Protocol servers for legacy apps. A built-in SMTP submission server (MSA) and an IMAP proxy let existing clients reach OAuth2-only mailboxes without implementing OAuth2 themselves.
- Admin interface. Server-rendered dashboard with light and dark themes, an embedded API reference, queue inspection, and logs.
- Admin authentication. Password, passkeys (WebAuthn), TOTP two-factor, and SSO through Okta or any OpenID Connect provider (Keycloak, Authentik, Entra ID, Google).
- Operations. Prometheus metrics, structured logging, and a 7-language admin UI.
Quickstart
Screenshots
Requirements
- Node.js - version 20 or newer (only when running from source; the prebuilt binaries and the Docker image bundle their own runtime)
- Redis - any version
[!IMPORTANT]
EmailEngine uses Redis as its primary database, not as a cache. Set maxmemory-policy to noeviction and give Redis enough memory for your workload - with any other policy Redis can drop sync state, which makes already-synced messages look new and generates duplicate webhooks.
Redis Cluster and Amazon ElastiCache are not supported. Use a standard Redis primary instance. EmailEngine warns about all of the above on the dashboard when it detects them.
[!NOTE]
While Redis does not officially support Windows, alternatives like Memurai are available.
[!TIP]
Minimize the latency between EmailEngine and Redis by running both on the same machine or in the same data center. Since EmailEngine runs a separate Redis command for each message in a folder during syncing, high latency can lead to slow sync times for folders with many messages.
Documentation
Configuring EmailEngine
Refer to the configuration documentation for details on setting up EmailEngine. ENVIRONMENT.md lists every environment variable EmailEngine reads, with its default.
App Access
By default, EmailEngine only allows connections from localhost. To enable external access, either edit the config file or use the CLI option --api.host="0.0.0.0". Ensure to secure external access with a firewall or proxy to allow only trusted sources.
This is the beginning of the README. Read the rest at the original. Read the full README ↗
