Connect Lettr to your AI agent

Messaging 60 actions available

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

We set up the connection using your own Lettr account, with keys you control, and keep it running. Your agent picks it up and starts doing the work.

Book a setup call → See pricing
Actions

What your agent can do in Lettr

Each one is a real action the agent can take on its own, the same things a person clicking around Lettr could do. Read-only by default; write actions are confirmed against your policy.

  • 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 Sent Emails Return one cursor-controlled page of sent emails, optionally filtered by recipient and date range.
  • List Projects Return one cursor-controlled page of Lettr projects and their IDs for use with template operations.
  • 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 transition…
  • Send Email Immediately queue a transactional email to up to 50 recipients using inline content or a Lettr template. This is an irreversible external send.
  • Unschedule Campaign Cancel a scheduled campaign send and return the campaign to draft. The campaign must still be scheduled; this cannot stop one already preparing or sending.
  • Update Audience Contact Change a contact's email, subscribed or unsubscribed status, or selected custom property values. Provide at least one of email, status, or properties; a null value inside properties removes that property.
  • Update Audience List Rename an audience list while preserving its contacts.
  • Update Audience Property Set or clear a custom contact property's fallback value. Its name and data type cannot be changed.
  • Update Audience Segment Change a dynamic segment's name, optional audience-list restriction, or complete AND-of-OR condition definition. Provide at least one of these mutable fields; setting list_id to null removes the list restriction.
  • Update Audience Topic Change a subscription topic's name, description, or public/private visibility. Provide at least one of these mutable fields; setting description to null clears it. Its default subscription behavior cannot be changed.
  • Update Template Rename an email template's metadata without publishing a new version.
  • Update Webhook Partially update a webhook's name, callback URL, authentication, selected events, or active state. Provide at least one field to update.
  • Verify Domain Run Lettr's DNS verification for a registered domain and return DKIM, CNAME, DMARC, SPF, and ownership results.
Setup

How we connect it

  1. 1

    Connect your account

    You create a key in Lettr, a key you create and control, and paste it in once. It lives in a secrets store on your server, not with us.

  2. 2

    Set the guardrails

    Read-only by default. You choose which write actions the agent may take, and anything outside that policy gets confirmed with you first.

  3. 3

    We keep it running

    Health checks on every connection, updates handled for you, and we watch the first week of activity to make sure the work lands.

FAQ

Lettr questions, answered.

With a key you create and control. You paste it in once, it is stored in a secrets store on your server, permissions are scoped to the minimum the agent needs, and you can revoke it at any time.
The actions Lettr's API allows, the same things a person clicking around the app could do. Connections start read-only by default; write actions are confirmed against the policy you set before the agent takes them.
Connections are priced per tool on top of the base plan. Some are included, some are premium. See pricing for how connection charges work.
Standard tools are ready inside 7 business days of the setup call. We test the connection end to end, walk you through how the agent uses it, and watch the first week of activity.

Ready to put Lettr to work?

Tell us what your team runs on. We set up the connection, secure it, and your agent takes it from there.

Book a setup call → Browse all connections

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