Truespar Sentio
Full email infrastructure built in Rust. SMTP send and receive, REST API for every operation, multi-tenant isolation, and AI-native processing - self-hosted and production-ready.
Send and Receive
Full bidirectional SMTP - not just a sending API. Sentio accepts inbound email, processes it, and exposes it through a REST API. Replace your entire mail stack, not just the outbound relay.
API-First
100+ REST endpoints cover every operation - send, receive, search, filter, manage domains, configure routing, and query delivery status. Every action available through SMTP is also available through HTTP.
Multi-Tenant
Isolated tenants with separate domains, mailboxes, routing rules, and API keys. One Sentio deployment serves multiple organizations without data leakage or configuration bleed.
Complete Mail Platform
DKIM, SPF, DMARC
Automatic DKIM signing on outbound, SPF validation on inbound, and DMARC policy enforcement. Email authentication is built in - not a configuration exercise.
TLS Everywhere
STARTTLS for SMTP connections, HTTPS for the API, and certificate management for custom domains. All connections are encrypted by default - plaintext requires explicit opt-in.
AI-Native
Built with AI processing in mind from day one. Inbound email can be classified, summarized, and routed by language models as part of the delivery pipeline - not as a bolted-on integration.
PostgreSQL + Redis + RabbitMQ
Battle-tested storage stack. PostgreSQL for persistent state, Redis for caching and rate limiting, RabbitMQ for async job processing. Each component is replaceable.
13 Crates
Modular Rust workspace - SMTP server, SMTP client, MIME parser, DNS resolver, queue manager, API server, and more. Each crate has a single responsibility and can be tested independently.
Production Ready
Sentio is a production system handling real email traffic. Not a prototype, not a side project - a deployed platform that has been hardened through real-world use.
How Sentio Compares
| Sentio | Postfix | SendGrid | |
|---|---|---|---|
| Capabilities | |||
| Send email | SMTP + API | SMTP | API + SMTP |
| Receive email | SMTP + API | SMTP | Inbound parse |
| REST API | 100+ endpoints | - | Full |
| AI processing | Built-in | - | - |
| Architecture | |||
| Language | Rust | C | N/A (SaaS) |
| Multi-tenant | Native | Manual vhosts | Subusers |
| Self-hosted | Full control | Full control | SaaS only |
| Security | |||
| DKIM signing | Automatic | Config required | Automatic |
| SPF validation | Built-in | External | Built-in |
| TLS | Default on | Config required | Always |
Own Your Email
Stop renting your email infrastructure. Sentio runs on your hardware, under your control, with no per-message fees and no vendor lock-in.