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Documentation Index

Fetch the complete documentation index at: https://docs.lettr.com/llms.txt

Use this file to discover all available pages before exploring further.

Lettr’s Audience system lets you manage contacts, organize them into lists, create dynamic segments, and send email campaigns. It works alongside the transactional sending API — transactional emails are triggered by user actions, while campaigns are sent proactively to groups of contacts.
Audience features require a Marketing plan. All accounts include a free 500-contact tier.

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Core Concepts

Contacts

Individual email addresses with custom properties, subscription status, and list memberships.

Segments

Dynamic groups of contacts that update automatically based on conditions you define.

Campaigns

Email campaigns sent to lists, segments, or your entire audience.

Billing

Contact-based marketing plans and pricing.

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Key Features

  • Custom contact properties — Define string, number, boolean, date, and JSON properties to store any data on your contacts
  • CSV import and export — Bulk import contacts from CSV files with column mapping; export contacts to CSV for external use
  • Double opt-in — Optional confirmation email flow for GDPR-compliant list building
  • Subscription topics — Let contacts subscribe and unsubscribe per topic for granular preference management
  • AI segment builder — Describe your target audience in natural language and let the AI generate the segment conditions
  • Campaign analytics — Track opens, clicks, bounces, and unsubscribes per campaign

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Getting Started

1

Subscribe to a Marketing Plan

All accounts include a free 500-contact tier. For larger audiences, upgrade from Settings → Billing.
2

Add Contacts

Import contacts via CSV or add them through the API. Each contact needs at minimum an email address.
3

Organize Your Audience

Create lists to group contacts manually, or create segments to group contacts dynamically based on conditions.
4

Send a Campaign

Choose your audience, build your email content, preview, and send or schedule your campaign.

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API Access

Audience resources are available through the API with the audience:read and audience:write scopes. You can manage contacts, lists, and segments programmatically.