Resend

Recently shipped Message-ID inclusion in all webhooks and email endpoints for threading, plus an emoji picker and suppression list management in the Node SDK.

All email webhooks and GET endpoints now include message_id for threading. Pass it as In-Reply-To and References on your next send so Gmail, Outlook, and Apple Mail group replies into the same conversation. Reply matching and cross-system correlation follow naturally.

The MCP server gained idempotency support and domain claim tools. The hosted remote MCP server (with OAuth) now supports idempotencyKey on send-email and send-batch-emails, surfaces message_id in email tool outputs, and accepts a display-name From header. Tools for claiming domains and configurable API/host/allowedHosts settings shipped in recent versions.

React Email’s preview toolbar now has a Props tab for live-editing template props. Edits re-render the preview without changing PreviewProps; invalid JSON is flagged inline. The email build command accepts a custom export extension (--extension .blade.php). Per-module build output with sideEffects: false lets bundlers tree-shake unused components — importing a component no longer pulls in prismjs, marked, or tailwindcss unless actually used. The preview toolbar is now responsive across desktop and mobile. Editor bug fixes include applying inline styles stored on the code mark and skipping filler paragraphs when composing emails.

Node SDK v6.18.0-canary.0 added resend.suppressions with add, get, list, remove, and batch add/remove methods for managing suppression list entries.

The Auth0 provider integration, bar/line/area chart component, AI @-mention context injection, Logs API, Python async support, and the Claude Code plugin remain active and stable.