One Rust engine for IMAP, Gmail and Microsoft Graph — unified REST and gRPC APIs, event-driven sync, and zero external dependencies.
Sync thousands of mailboxes from a single ~60 MB binary that runs entirely on your own infrastructure.
Connects to
Platform
Stop stitching together IMAP clients, OAuth flows, queues and webhook plumbing. RustMailer gives you the whole stack as a single self-hosted service.
One typed API surface for every provider. OpenAPI, Swagger, ReDoc and generated gRPC clients included.
IMAP, Gmail API and Microsoft Graph behind a single account model — no per-provider protocol code.
New mail, flag changes and deletions delivered through webhooks or NATS with at-least-once semantics.
Filter, reshape and enrich every event with Vector Remap Language before it leaves the engine.
Token refresh, encrypted credential storage and per-provider client configuration out of the box.
Prometheus metrics for sync, sending, webhooks and task queues — plus a built-in webmail inspector.
Developer experience
Call a mailbox like any other service. RustMailer hides MIME encoding, provider quirks, token refresh and mailbox state behind a predictable, typed interface.
POST /api/v1/accounts/42/messages
Authorization: Bearer $RUSTMAILER_TOKEN
Content-Type: application/json
{
"to": ["dev@example.com"],
"subject": "Welcome to RustMailer",
"template": "welcome"
}Self-hosted
Powerful infrastructure for email-based apps.
Webmail
Lightweight webmail UI for viewing synced emails and testing template deliveries.
API
Powerful REST & gRPC APIs with rich docs and flexible data handling.
Events
Email events delivered via Webhook or NATS — new messages, flags, and more.
VRL
Leverage VRL to gain full control over email event data — from filtering to payload transformation.
OAuth2
Connect Gmail, Outlook, and others without handling tokens or refresh logic.
Sending
Built for flexibility and control
Observability
Gain full insight with detailed, out-of-the-box Prometheus metrics across all system components.
Customers
Stop wrestling with protocols, provider APIs and webhook plumbing. Let RustMailer handle the infrastructure.
After struggling with other unified email middleware services — both paid and open-source — we were frustrated with scalability, forced sales calls and deceptive pricing. RustMailer was a breath of fresh air.
We initially hesitated to choose a relatively new middleware, but it met our requirements better than any established alternative. The team doesn't just respond to requests — they actively collaborate with us, ship the features we need, and make us feel like partners rather than another customer.
Use cases
From SaaS products to hosting providers, RustMailer removes months of email infrastructure work from the roadmap.
Connect and manage users’ mailboxes to gain real-time insight into their communication flows.
Ship bespoke email features for clients — newsletters, campaign systems and tailored webmail.
Deliver custom webmail experiences tightly integrated with your hosting platform.
Automate support and information mailboxes, reducing manual workload and response times.
Automate warmup across multiple accounts to improve sender reputation and inbox placement.
Aggregate user email securely to fuel data-driven models and email-native intelligence.
Manage postmaster and abuse mailboxes for compliance and monitoring from one control plane.
Use RustMailer as a secure IMAP/SMTP gateway between legacy systems and modern providers.
Scale personalized campaigns with automated sending and reply handling for prospect engagement.
FAQ
Everything about licensing, self-hosting and how RustMailer fits into your stack.
Still curious? Talk to us.
Get started
Deploy RustMailer on your own infrastructure and get a reliable email backend without the protocol plumbing.
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