[bjarn]

What changed

Non-breaking; suggested bump: minor.

• Regenerated src/generated/ from the latest API spec.
• New messages.resend(messageId, body?, options?) for POST /messages/{messageId}/resend. It sends a sent message again as a new message with its own ID, to every original recipient or to the recipients given. Like messages.process, it takes an idempotencyKey option. Like reschedule and cancel, it uses the team token and falls back to the sending token when no team token is set.
• README: resend is listed in the Team API table, with a short example and the note on the token fallback.

API changes in the regenerated types

Change	Details
messages.resend endpoint	POST /messages/{messageId}/resend. Optional body ResendMessageRequest { recipients?: string[] } and optional Idempotency-Key header. Answers 202 with a PendingSendMailResponse. Errors: 401, 403, 404, 409, 410 (content no longer retained), 422, 429, 500. Accepts the team or the sending token.
MessageData.resent_from_message_id	Optional and nullable: resent_from_message_id?: string | null. The ID of the message this message resent; absent or null when the message is not a resend. Code that builds MessageData objects keeps compiling.
SendBatchMailItem	New batch item type: every SendMailRequest field plus an optional per-email idempotency_key (1-255 characters). SendBatchMailRequest is now SendBatchMailItem[] (was SendMailRequest[]).
POST /send/batch 409	The error body can now also be an ApiError (code IDEMPOTENCY_CONFLICT).
OperationTypes	Adds PendingSendMailResponse and ResendMessageRequest.

Usage

const lettermint = new Lettermint({ teamToken: process.env.LETTERMINT_TEAM_TOKEN });

// Every original recipient, no request body:
const resent = await lettermint.messages.resend('message-id');

// Some of the original recipients, safe to retry:
await lettermint.messages.resend(
  'message-id',
  { recipients: ['jane@example.com'] },
  { idempotencyKey: 'resend-order-1234' }
);

Checks

Run locally on Node 26.5.0:

• npm run lint: passed (33 files, no fixes)
• npm run type-check: passed
• npm run generate:check: generated files up to date (with the generator), and the header check passed without it
• npm run test:coverage: 316 passed, 8 suites
• Compatibility: the v3.1.0 test suite, plus a MessageData literal without the new field and an EmailMessage[] passed to sendBatch, type-checks against this branch (tsc -p tsconfig.test.json: no errors). The only failure is the v3.1.0 coverage test, which lists every operation and so misses resend, as expected
• npm run build: CJS, ESM and DTS builds succeeded
• npm run test:smoke: ESM import, CJS require and type declarations ok

Not run locally

• The Node 20, 22 and 24 CI matrix. Only Node 26 was run locally.

Suggested release tag

v3.2.0

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