Security starts with data ownership
Nestiel does not connect to SMTP or IMAP directly. All email IO flows through the Resend HTTP API; metadata and attachments live on your own infrastructure, with strict multi-tenant isolation.
Metadata in your own Postgres
Email, conversations, orgs, and member info live in your own Postgres — never locked into a third-party platform.
Attachments in the object storage you configure
Attachment binaries live in the object storage you configure (Aliyun OSS, S3-compatible, etc.), with placement and lifecycle under your control.
Strict multi-tenant isolation
Auth is driven by org and mailbox headers, so cross-org and cross-inbox access is strictly isolated.
No direct SMTP or IMAP
All sending, receiving, and delivery events go over the Resend HTTP API — no long-lived SMTP or IMAP channels in your service.
Webhook signature verification
Resend callbacks are trusted only after svix signature verification, and processed idempotently to prevent forgery and duplicates.
Org-level key management
The Resend API key and org LLM key are configured centrally at the org level, making rotation and control simple.
Data flow: always around your own infrastructure
Starting from your own domain, email IO flows through the Resend HTTP API, metadata lands in your Postgres, and attachments land in your object storage — no third party hosting your inbox for you.
Your domain
Send and receive from addresses like hello@yourdomain.com; the sending domain is verified in Resend.
Resend HTTP API
All sending, receiving, and delivery events flow through Resend's REST API.
Your Postgres (metadata · conversations)
Email metadata, conversations, and orgs live in your own Postgres.
Your object storage (attachments)
Attachment binaries live in the object storage you configure, under your control.
Your data stays in your own infrastructure
Honest boundaries
We do not promise what we cannot deliver. Credentials (Resend API key, object storage keys, LLM API key) assume a trusted runtime and are currently stored in plaintext in your database. Inbound email attachments are fetched from Resend on demand and may expire under its retention policy, while attachments on email you have sent are persisted to your own object storage. Nestiel does not offer end-to-end encryption — its security model rests on you owning and operating both your data and your infrastructure.
Frequently asked questions
Where is my email data stored?
Email metadata and conversations live in your own Postgres, and attachment binaries in the object storage you configure; Nestiel does not centrally host your email content.
How are tenants isolated?
Auth is driven by org / mailbox headers, and every list and detail endpoint is isolated by mailboxId, so cross-org and cross-inbox access is strictly blocked.
Do you support self-hosted deployment?
Yes — arranged offline with the developer; once deployed, the runtime and data stay entirely in your hands.
How are credentials stored?
In the interest of honesty: the Resend key, object-storage keys, and LLM key currently assume a trusted runtime and are stored in plaintext in your database, and there is no end-to-end encryption — the security model rests on you owning and operating your own data and infrastructure.
Start your team's email workflow
Connect your own domain and Resend account to begin. Data stays with you; capabilities scale with your org.