September 2026

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New features

• replyTo on transactional mail — POST /mail/send and POST /mail/send/batch now accept an optional replyTo field (a single address or an array of addresses). When set, replies from recipients route to those addresses instead of your verified from sender. Available in the REST API, TypeScript SDK (mail.send() / mail.sendBatch()), and Python SDK. See Send mail and Mail SDK. (by @yash-pouranik in #402)

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Bug fixes

• Empty mail bodies are now rejected up-front — Mail requests without any content (both html and text empty or whitespace) now fail validation with a 400 before hitting the mail queue, instead of enqueuing an empty message. Whitespace-only subjects are also rejected. See Send mail. (by @yash-pouranik in #402)