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://jentic.com/install.sh?src=apis&api=%2Fapis%2Flettermint.co%2Flettermint" | sh

Step 2: Agent machine

# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Flettermint.co%2Flettermint" | 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}

Subscribe to delivery, bounce, and inbound events with the /webhooks endpoints

GET STARTED

Start building with Lettermint Team API

Explore with Jentic One

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 your Jentic One instance. 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.

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.

Why Jentic?

What agents get from Jentic-routed access to this vendor.

Setup

Wiring the Lettermint Team API by hand means managing its bearer token, including per-project tokens you rotate, verifying DNS records for sending domains, and calling api.lettermint.co yourself. Through Jentic you install once, import the Lettermint Team API from the API Directory, store the token once, and your agent calls it.

Permission scoping

Lettermint puts the domain and project ids in the URL path (/domains/{domainId}/dns-records/verify, /projects/{projectId}/rotate-token), so a rule can pin your agent to one project or domain: it acts only on that resource. You choose the operations it may call, so destructive ones like token rotation or suppression changes are not included unless you add them.

Credential isolation

Your Lettermint bearer token is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.

Intent-based discovery

Agents search Jentic by intent such as 'verify a sending domain' or 'check why a message bounced', and Jentic returns the matching Lettermint operation with its input schema so the agent calls the right endpoint without browsing the reference docs.

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 with Jentic One, the self-hosted execution layer.

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 your Jentic One instance, 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.

Can I limit what my agent is allowed to do with the Lettermint Team API?

Yes. Because you run Jentic One yourself, your own rules decide which Lettermint operations and credentials your agent may use. Lettermint puts the domain and project ids in the URL path, such as /domains/{domainId}/dns-records/verify and /projects/{projectId}/rotate-token, so a rule can pin the agent to a single project or domain and let it act only on that resource. You also choose which operations are exposed, so destructive calls like POST /projects/{projectId}/rotate-token or POST /suppressions stay out of reach unless you explicitly add them.

Lettermint Team API

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

Agent-ready OpenAPI document · curated by JenticCommunicationsEmail Deliverybearer46 EndpointsREST

Know of an official OpenAPI document? Contribute it →

For Agents

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

Use for: I need to verify a new sending domain in Lettermint, Rotate the API token for one of our Lettermint projects, List the messages sent in the last 24 hours and their delivery status, Add an email address to the suppression list

Not supported: Does not handle SMS, push notifications, or marketing campaign design - use for transactional email sending, domain verification, and inbound parsing only.

Jentic publishes the only available OpenAPI specification for Lettermint Team API, keeping it validated and agent-ready. Lettermint is a transactional email platform that lets developers send messages, manage sender domains, organise projects, configure inbound routes, and react to delivery events through webhooks. The 46 endpoints cover team management, domain DNS verification, project-scoped API tokens, message inspection, suppression lists, and aggregate stats so an integration can run a multi-project email pipeline end to end.

Jentic One on Github View OpenAPI Document

Connect the Lettermint Team API to your agent

Capabilities

Start building with Lettermint Team API

Use Cases

Key Endpoints

Why Jentic?

Related APIs

FAQs

Lettermint Team API