# Lettr MCP

Vendor: Lettr  
Category: other  
Auth: API_KEY  
Composio slug: `lettr`

Lettr is an email and messaging platform for transactional delivery, templates, audiences, campaigns, domains, and webhooks.

## Tools

- **Attach Contacts to Lists** — Attach every combination of 1-1000 contacts and 1-50 audience lists, processing up to 50,000 contact-list pairs and reporting new and existing memberships.
- **Bulk Create Audience Contacts** — Create or recognize up to 1000 normalized, deduplicated contacts. Shared properties affect only newly created contacts; list_id applies to all contacts, including those that already exist.
- **Cancel Scheduled Email** — Cancel a scheduled email before its delivery time; cancellation is unavailable once processing has begun.
- **Create Audience Contact** — Create one audience contact with optional properties and list membership.
- **Create Audience Contact With Double Opt-In** — Create an unverified audience contact and irreversibly send an external confirmation email; the contact becomes subscribed only after confirming.
- **Create Audience List** — Create a uniquely named audience list for grouping contacts.
- **Create Audience Property** — Define a custom contact property with an immutable name and value type. Changing either later requires deleting and recreating the property.
- **Create Audience Segment** — Create a dynamic audience segment whose condition groups are ANDed while conditions inside each group are ORed.
- **Create Audience Topic** — Create a public or private subscription topic with an immutable opt-in or opt-out default.
- **Create Domain** — Register a sending domain and return the DNS configuration needed to verify it.
- **Create Template** — Create and publish an email template from either custom HTML or Topol editor JSON, extracting its merge tags.
- **Create Webhook** — Create an active event webhook using no authentication, HTTP Basic credentials, or OAuth 2 client credentials.
- **Delete Audience Contact** — Permanently delete one audience contact and its associated memberships.
- **Delete Audience Lists** — Permanently delete between 1 and 50 audience lists in one request.
- **Delete Audience Property** — Permanently delete a custom contact-property definition.
- **Delete Audience Segment** — Permanently delete one dynamic audience segment.
- **Delete Audience Topic** — Permanently delete one audience subscription topic.
- **Delete Domain** — Permanently remove a sending domain from Lettr and SparkPost so it can no longer send email.
- **Delete Template** — Permanently delete an email template and all of its versions.
- **Delete Webhook** — Permanently remove a webhook so Lettr stops delivering events to it.
- **Detach Contacts from Lists** — Detach every combination of 1-1000 contacts and 1-50 audience lists, reporting removed and absent memberships.
- **Get Audience Contact** — Retrieve one contact's email, status, custom properties, list memberships, and topic subscriptions by ID.
- **Get Audience List** — Retrieve one audience list and its current contact count by ID.
- **Get Audience Property** — Retrieve one custom contact-property definition and its fallback value.
- **Get Audience Segment** — Retrieve one dynamic segment's list restriction, complete AND-of-OR condition definition, and cached contact count.
- **Get Audience Topic** — Retrieve one subscription topic's defaults, visibility, and current contact count.
- **Get Campaign** — Retrieve one campaign's name, subject, sender and reply-to configuration, schedule, rendered HTML, lifecycle state, recipient counts, and engagement statistics. The campaign's audience definition is not returned.
- **Get Domain** — Retrieve one sending domain's send readiness, DNS records, provider detection, and verification status.
- **Get Email** — Retrieve a sent email's delivery state, recipients, schedule metadata, and events by request ID. The configurable event date range defaults to the last 10 days, not the email's complete event history.
- **Get Scheduled Email** — Retrieve a scheduled email's current state and events by transmission ID, including after it has been processed.
- **Get Template** — Retrieve an email template's metadata, active HTML or editor JSON content, and version counts by slug.
- **Get Template Merge Tags** — Return required and optional merge tags for a template's active or specified version before sending with substitution data.
- **Get Webhook** — Retrieve one webhook's target, enabled state, event selection, authentication mode, and latest delivery status.
- **List Audience Contacts** — Return one cursor-controlled page of contacts, optionally filtered by search text, status, list, or segment.
- **List Audience Lists** — Return one cursor-controlled page of audience lists with each list's contact count.
- **List Audience Properties** — Return one cursor-controlled page of custom contact-property definitions and fallback values.
- **List Audience Segments** — Return one cursor-controlled page of dynamic audience segments, including their complete AND-of-OR condition definitions, optionally filtered by list.
- **List Audience Topics** — Return one cursor-controlled page of subscription topics with defaults, visibility, and contact counts.
- **List Campaign Events** — Return one cursor-controlled page of a campaign's delivery and engagement events, with event, recipient, and time filters. An empty items page can still have a next_cursor; continue until next_cursor is null.
- **List Campaigns** — Return one cursor-controlled page of campaigns with complete delivery and engagement statistics, optionally filtered by lifecycle status.
- **List Domains** — Return all sending domains with approval, DNS verification, and send-readiness status.
- **List Email Events** — Return one cursor-controlled page of delivery and engagement events across sent emails, with event, recipient, transmission, bounce, and date filters.
- **List Projects** — Return one cursor-controlled page of Lettr projects and their IDs for use with template operations.
- **List Sent Emails** — Return one cursor-controlled page of sent emails, optionally filtered by recipient and date range.
- **List Templates** — Return one cursor-controlled page of email templates for a project or the team's default project.
- **List Webhooks** — Return all event webhooks with target, enabled state, event selection, authentication mode, and latest delivery status.
- **Publish Template Version** — Create and activate a new version of an existing email template from exactly one of HTML or Topol editor JSON, optionally renaming the template atomically.
- **Schedule Campaign** — Schedule a campaign for future delivery or reschedule it. The campaign dispatches automatically at that time unless it is unscheduled first.
- **Schedule Email** — Create a transactional email scheduled 5 minutes to 3 days in the future; it remains cancellable until processed.
- **Send Campaign** — Immediately and irreversibly start sending a sendable draft campaign to its resolved audience. Only call after confirming the campaign's audience, subject, sender email, and content. A successful 202 response transitions the campaign asynch

## Setup

1. Create or open a Switchy Project.
2. Open Integrations and connect Lettr.
3. Authorise through api_key.
4. Teammates can now @-mention Lettr tools in chat.

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Last verified: 2026-09-03T02:00:04.194Z  
Canonical URL: https://switchy.build/directory/mcps/lettr