Lettermint Team API

Name: Lettermint Team API
Brand: Lettermint Team API
Availability: InStock

★ Only Publicly Available OpenAPI DocumentCommunicationsEmail Deliverybearer46 EndpointsREST

For Agents

Send and inspect transactional email through Lettermint, manage verified sending domains, project-scoped tokens, suppressions, and webhooks for delivery events.

Install Jentic One Beta

Connect the Lettermint Team API to your agent

Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Lettermint Team API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.

Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.

Step 1: Jentic One Host machine

# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh

Step 2: Agent machine

# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register       # connects your agent to your Jentic One instance

Jentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.

Capabilities

What an agent can do with Lettermint Team API.

Verify and manage sending domains with DNS record checks via /domains and /domains/{domainId}/dns-records/verify

Organise sending into projects, rotate per-project API tokens, and manage members under /projects

Inspect delivered messages including headers, HTML, plain text, and event timeline at /messages/{messageId}

GET STARTED

Start building with Lettermint Team API

Explore with Jentic

View OpenAPI Document

Use Cases

Patterns agents use Lettermint Team API for, with concrete tasks.

★ Multi-project email infrastructure

A SaaS company wants separate sending reputations for product, billing, and marketing. Using POST /projects to create each silo, POST /projects/{projectId}/rotate-token to issue scoped credentials, and the /domains endpoints to verify a dedicated sending domain per project, the team isolates concerns so a marketing dispute does not affect transactional delivery. This mirrors the multi-tenant pattern used by larger ESPs without leaving Lettermint.

Create a project named 'billing-prod' via POST /projects, rotate its API token with POST /projects/{projectId}/rotate-token, and add the verified domain to it via PUT /domains/{domainId}/projects.

Delivery debugging and inbox forensics

When a customer complains they never received an email, support needs to inspect what was sent and what happened to it. The /messages/{messageId} endpoint returns metadata, and /messages/{messageId}/events, /messages/{messageId}/source, /messages/{messageId}/html, and /messages/{messageId}/text return the event timeline and the original payloads. Engineers can confirm the message was sent, see if it bounced, and read the exact body that left the system.

For messageId 'msg_abc123', call GET /messages/{messageId}/events and GET /messages/{messageId}/html to confirm the bounce reason and inspect the rendered body.

Inbound parsing into application logic

Product teams that want users to reply by email (support tickets, comment-by-email) configure inbound routes with POST /projects/{projectId}/routes and verify the inbound domain via POST /routes/{routeId}/verify-inbound-domain. Lettermint then parses incoming mail and posts the structured payload to the team's webhook so the application can create a ticket or thread reply automatically.

Create an inbound route on projectId 'proj_42' with POST /projects/{projectId}/routes pointing at https://example.com/inbound, then verify the inbound domain.

AI agent transactional email via Jentic

An AI customer-success agent needs to send order confirmations and follow-ups through the company's verified Lettermint domain. Through Jentic the agent searches for 'send a transactional email' or 'check delivery status', loads the matching Lettermint operation, and executes with the bearer token held in the Jentic vault. The agent gets reliable delivery without ever seeing the raw API token.

Use Jentic to search 'check message delivery status', load GET /messages/{messageId}, and return whether the latest order confirmation was delivered or bounced.

Key Endpoints

46 endpoints — jentic publishes the only available openapi specification for lettermint team api, keeping it validated and agent-ready.

METHOD

PATH

DESCRIPTION

POST

/domains

Add a sending domain.

POST

/domains/{domainId}/dns-records/verify

Verify domain DNS records.

GET

/messages

List sent messages.

GET

/messages/{messageId}/events

Get message event timeline.

POST

/projects

Create a project.

POST

/projects/{projectId}/rotate-token

Rotate a project API token.

POST

/webhooks

Create a webhook subscription.

POST

/suppressions

Add a recipient to the suppression list.

POST

/domains

Add a sending domain.

POST

/domains/{domainId}/dns-records/verify

Verify domain DNS records.

GET

/messages

List sent messages.

GET

/messages/{messageId}/events

Get message event timeline.

POST

/projects

Create a project.

Why Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

Lettermint Team API bearer tokens — including rotated project-scoped tokens — are stored encrypted in the Jentic MAXsystem vault. Agents call /messages, /domains, and /webhooks under scoped access without seeing the raw bearer secret.

Intent-based discovery

Agents search by intent (e.g., 'verify a sending domain', 'check why a message bounced') and Jentic returns the matching Lettermint operation across the 46 endpoints with its full input schema.

Time to first call

Direct integration: 1-2 days for token handling, domain verification, webhook signing, and inbound-route setup. Through Jentic: under an hour to search, load, and execute the first call.

FAQs

Specific to using Lettermint Team API through Jentic.

Why is there no official OpenAPI spec for Lettermint Team API?

Lettermint does not publish a maintained OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Lettermint via structured tooling. It is validated against the live API and kept up to date. Get started at https://app.jentic.com/sign-up.

What authentication does the Lettermint Team API use?

The API uses HTTP Bearer authentication with a Team API token, generated from the team settings page. Through Jentic the token is held in the MAXsystem vault, so the agent calls /domains, /messages, and /projects without ever holding the raw secret.

Can I run separate sender reputations per project with Lettermint?

Yes. POST /projects creates an isolated project, POST /projects/{projectId}/rotate-token issues a project-scoped credential, and PUT /domains/{domainId}/projects attaches a verified sending domain. This separates marketing, transactional, and billing sends so deliverability problems on one stream do not affect the others.

What are the rate limits for the Lettermint Team API?

Lettermint does not publish exact rate-limit numbers in the public spec. Treat sending and listing endpoints as standard HTTP APIs — implement pagination on /messages, batch suppression updates, and back off on 429 responses with the Retry-After header.

How do I subscribe to bounce events through Jentic?

Run 'pip install jentic', search for 'create a webhook for email events', and Jentic returns POST /webhooks. Load the schema, supply the callback URL and event types (e.g., bounce, complaint, delivered), and execute. Lettermint will then POST event payloads to your endpoint.

Can I receive replies to outgoing emails programmatically?

Yes. Configure an inbound route with POST /projects/{projectId}/routes pointing at your webhook, then call POST /routes/{routeId}/verify-inbound-domain to validate the receiving MX setup. Lettermint will parse incoming mail and post structured payloads to your endpoint.

Lettermint Team API

Connect the Lettermint Team API to your agent

Capabilities

Start building with Lettermint Team API

Use Cases

Key Endpoints

Why Jentic?

Related APIs

FAQs