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Lists & Segments

Organize your audience into targeted groups for precise campaign delivery.

Bulk CSV Import

Migrate your existing audience by uploading a CSV file.

Recommended CSV Format

email,firstName,lastName,metadata
john@example.com,John,Doe,"{""source"": ""website""}"
jane@company.com,Jane,Smith,"{""plan"": ""pro""}"
  • • Mapping: You can map custom headers to Transmit fields during the import process.
  • • Deduplication: Existing contacts are automatically updated based on their email address.

Custom Metadata

Store arbitrary data with each contact using JSON metadata. This can be used for personalization or internal tracking.

// API example: Update contact with metadata
await transmit.contacts.update(id, {
  metadata: {
    lastPurchase: "2025-12-01",
    loyaltyTier: "Gold"
  }
});