Self-host rustmailer
1.7.6Email middleware unifying IMAP, SMTP, Gmail and Graph APIs
- Stars
- 514
- Ports
- 15630 (HTTP/REST API and Web UI), 16630 (gRPC API)
rustmailer/rustmailer
What is rustmailer?
RustMailer is a self-hosted email middleware for developers who need to add email sync and sending to their applications. It connects to IMAP, SMTP, Gmail API, and Microsoft Graph API through a unified REST and gRPC interface. A built-in web client and admin dashboard let you inspect synced mailboxes, view headers, and test templates. Features include multi-account IMAP sync with incremental UID-based strategy, SMTP sending with connection pooling and Handlebars templates, OAuth2 flows for Gmail and Outlook with automatic token refresh, webhook and NATS event delivery with VRL scripting for payload transformation, open and click tracking, and Prometheus metrics. It runs as a single ~60MB Rust binary with no external dependencies like Redis or databases, deployable via Docker or direct binary. The code is source-available on GitHub but requires a paid license for production use after a 14-day free trial.
Should you self-host rustmailer?
rustmailer scores 44/100 on selfhost.directory (how scoring works) and ranks #81 of 106 in Email. It has 514 GitHub stars.
It shipped 9 stable releases in the past year. The latest, 1.7.6, came out on 16 October 2026. New versions land roughly every 10 days.
Setup is moderate: expect some configuration beyond a single command. An official Docker image is available. It is Other-licensed and written mostly in Rust.
Its closest alternative on selfhost.directory is Listmonk (80/100, 24 017 stars). It scores higher overall, so compare the two before you pick. See rustmailer vs Listmonk side by side.
Features
- Built-in webmail client and admin dashboard
- Email templates with Handlebars
- Gmail API integration
- Microsoft Graph API integration
- Multi-account IMAP synchronization
- NATS event streaming
- OAuth2 authentication flow
- Open and click tracking
- Prometheus Metrics
- Proxy Support
- REST and gRPC APIs
- SMTP sending with connection pooling
- Webhook delivery with VRL scripting
rustmailer README
FAQ
What are the payment or purchase options?
Licenses are purchased via embedded Stripe Checkout after signing in via Clerk or OAuth provider.
Can I customize webhook events in RustMailer?
Yes, webhook payloads can be filtered and transformed using VRL (Vector Remap Language) scripts per account or globally.
What dependencies does RustMailer require?
RustMailer runs as a single binary with no external dependencies like Redis or databases required.
How does RustMailer handle email syncing?
RustMailer performs periodic full or incremental synchronization of IMAP folders using UID-based strategy, not real-time push.
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