---
title: "Not open yet: reply to a received email."
method: POST
path: "/emails/receiving/{id}/reply"
tags: ["emails"]
---

# Not open yet: reply to a received email.

`POST /emails/receiving/{id}/reply`

## Request

- Base URL: `https://api.agentisend.com`
- URL: `https://api.agentisend.com/emails/receiving/{id}/reply`
- Auth: HTTP bearer

Threads on In-Reply-To and References, and runs every send check.

## Path parameters

- `id` string, uuid, required

## Headers

- `Idempotency-Key` string
- `Resend-Idempotency-Key` string

## Request body

- PostEmailsReceivingByIdReplyBody
  - `from` string: Sender. Omit it to reply from the address the message was sent to.
  - `html` string: HTML body. Provide html or text.
  - `text` string: Plain-text body. Provide html or text.
  - `subject` string: Subject. Omit it and the reply uses Re: plus the original subject.
  - `cc` union: Copy recipients.
    - string
    - string[]
  - `bcc` union: Blind copy recipients.
    - string
    - string[]

## Response `201`

Success

- PostEmailsReceivingByIdReplyReply
  - `id` string, uuid, required
  - `simulated` boolean, required
  - `warnings` object[], required
    - `code` string, required
    - `message` string, required
    - `fix` string, required

## Other responses

- `400`: The request is malformed or a field failed validation. Codes: validation_error, invalid_idempotency_key, invalid_cursor, plan_not_purchasable, stripe_signature_invalid, support_upload_rejected, sign_in_check_required.
- `401`: No usable credential was sent. Codes: missing_api_key, session_required, mfa_required.
- `402`: A budget, quota or plan limit would be exceeded. Codes: overage_cap_reached, daily_limit_reached, agent_budget_exceeded, plan_limit_reached.
- `403`: The credential may not do this, or the account or key is stopped. Codes: sending_domain_blocked, young_domain_held, domain_sending_disabled, domain_not_verified, onboarding_recipient_not_a_member, onboarding_sender_unavailable, account_suspended, account_sandboxed, human_action_required, csrf_origin_rejected, charge_not_this_account, invalid_api_key, restricted_api_key, insufficient_role, invite_email_mismatch, domain_scope_violation, dedicated_ip_assigned_by_us, approval_required, staff_review_required, trust_paused, kill_switch_active.
- `404`: Nothing with this id exists on the account. Codes: billing_customer_missing, not_found, session_expired, support_ticket_not_found.
- `409`: The request conflicts with the current state. Codes: domain_already_exists, template_name_taken, template_alias_taken, template_in_use, segment_in_use, contact_resubscribe_required, email_still_scheduled, domain_verified_elsewhere, domain_not_claimable, return_path_subdomain_in_use, overage_not_on_plan, term_not_on_sale, subscription_active, portal_change_unavailable, already_in_account, idempotency_in_flight, idempotency_payload_mismatch, approval_expired, support_closed, support_reopen_expired, support_merge_conflict, support_reply_too_soon.
- `413`: The request body is larger than this operation accepts. Codes: payload_too_large, support_upload_too_large.
- `415`: The request body is not JSON. Codes: unsupported_media_type.
- `422`: A field is well formed but was refused. Codes: missing_required_field, invalid_from_address, invalid_parameter, invalid_attachment, invalid_region, tracking_subdomain_unverified, tracking_subdomain_cannot_be_removed, domain_field_immutable, open_tracking_on_transactional, header_replaced, html_clipped_by_gmail, link_domain_listed, domain_blocklisted, mailbox_provider_domain, onboarding_shape_refused, dkim_key_mismatch, domain_check_window_expired, spf_conflict, spf_lookup_limit, review_sandbox_recipient_only, suppressed_recipient, content_refused, recipient_blocklisted, last_owner_required, seat_limit_reached, invite_not_valid, key_budget_exceeds_plan, domain_limit_reached, webhook_endpoint_limit_reached.
- `429`: A rate, quota or ramp ceiling was reached. Codes: onboarding_daily_cap_reached, trust_throttled, invite_limit_reached, rate_ceiling_exceeded, daily_quota_exceeded, monthly_quota_exceeded, rate_limit_exceeded, support_rate_limited.
- `500`: Something failed on our side. Codes: internal_server_error.
- `503`: A dependency is unavailable for a moment. Codes: dns_unreachable, service_unavailable, billing_not_configured, rate_limiter_unavailable, sending_paused_everywhere, support_draft_unavailable.

---

[API](https://skmtc.dev/agentisend/apis/agentisend-api.md) · [All operations](https://skmtc.dev/agentisend/apis/agentisend-api/llms.txt) · [OpenAPI document](https://skmtc.dev/agentisend/apis/agentisend-api/revisions/3066dda62a56?raw)