---
title: SMTP
description: Send MIME email over explicit TLS SMTP with protocol-level recipient outcomes.
---

Import `smtpEmailLayer` from `@corven/email-sdk/smtp` to provide the common `Email` service for this account.

## Configure the account

```ts
import type { Redacted } from "effect";
import { smtpEmailLayer } from "@corven/email-sdk/smtp";

export const configuredSmtpAccount = (username: Redacted.Redacted, password: Redacted.Redacted) =>
  smtpEmailLayer({
    authentication: { _tag: "Plain", password, username },
    helloName: "app.example.test",
    host: "smtp.example.test",
    mailFlow: "ProviderUnmodified",
    port: 465,
    security: "ImplicitTls",
  });
```

SMTP manages its own explicit socket/TLS transport; it does not need an HTTP client.

## Message behavior

- Configure an explicit host, port, helloName and ImplicitTls or StartTls security mode. Plain and Login authentication require Redacted credentials; None is also explicit.
- Connecting to an IP requires an explicit certificate serverName. The adapter does not support an unencrypted SMTP mode.
- Attachments use explicit MIME types; inline CIDs must be qualified. Repeated custom headers are supported, but metadata, tags and provider scheduling are not.
- RCPT and DATA evidence can produce partial recipient outcomes. A final acknowledgment is not inbox delivery, and a lost DATA acknowledgment can leave the outcome unknown.

## Idempotency

SMTP has no native send key support in this SDK. Reopening a connection cannot prove that a previous transaction was not accepted.

Read [field support](/providers/field-support) before switching accounts, and [receipts and retries](/reliability) before adding recovery behavior. Configuration and local validation do not authenticate the account or prove delivery.