How do I reply to an email my agent received?

Reply to an email your agent received with POST /emails/receiving/{id}/reply, which threads on the stored headers. The recipient is the original sender. In-Reply-To and References are copied from the stored message.

The call

Omit from to reply from the address the message was sent to. Omit subject and the reply uses Re: plus the original subject. Send text or html. cc and bcc are optional. Budgets, the kill switch, suppressions and the sending-domain check all apply, the same as POST /emails.

curl -sS -X POST https://api.agentisend.com/emails/receiving/9c8f8f0e-3d1a-4d3f-9a1e-2b7c1a0f5e42/reply \
  -H "Authorization: Bearer $AGENTISEND_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{"text":"Thanks — the details are attached."}'

201
{
  "id": "9c8f8f0e-3d1a-4d3f-9a1e-2b7c1a0f5e42",
  "simulated": false,
  "warnings": []
}

The headers

This route writes In-Reply-To and References from the stored message, so a body that also sends those headers does not replace them. GET /emails/receiving/{id} shows the message id they point at. GET /emails/receiving/threads groups the conversation.

Mail that lives in some other inbox is POST /emails with those two headers copied from the message you are answering. This page is the route for a message stored on your account. Agents connected over the agent connection use reply_to_email, which calls the same route.

Next

• Email for AI agents
• How do I receive email at my own domain?
• Receiving and replying

Written by the AgentiSend team.