Properties
| Name | Type | Description |
|---|---|---|
| attachments | array | File attachments (base64 in each item's data). Limits: at most 10 attachments, each ≤ 10 MiB decoded, and ≤ 25 MiB decoded combined. Exceeding the count → 400 invalid_request; exceeding a size → 413 p |
| bcc | array | Additional Bcc recipients. The final message is limited to 50 recipients across to, cc, and bcc combined. Each recipient string (display name + address combined) is limited to 320 characters. The addr |
| cc | array | Additional Cc recipients. The final message is limited to 50 recipients across to, cc, and bcc combined. Each recipient string (display name + address combined) is limited to 320 characters. The addre |
| conversation_id | string | Caller-assigned application conversation/grouping id override. This value is independent of email thread topology, which is derived from the referenced message. At most 200 characters — deliberately t |
| html | string | |
| quote_history | boolean | Beta: when true, the server appends the referenced message as mail-client-style quoted history beneath the reply body — an 'On |
| reply_all | boolean | |
| reply_to | object | Sets the Reply-To header — where replies to this message are directed. Either a single RFC 5322 address (optionally with a display name, e.g. "Support |
| send_at | string | Beta: scheduled sending may change before it is declared stable. Optional scheduled-send time (RFC 3339 with a UTC offset). When set to a future instant the reply is accepted immediately and returns s |
| text | string | |
| unsubscribe | object | Beta: opts this message into e2a-managed unsubscribe handling. This field may change before it is declared stable. |
JSON Schema
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"$id": "https://artifacts.apis.io/e2a-dev/json-schema/e2a-dev-reply-request-schema.json",
"title": "ReplyRequest",
"x-generated": "2026-10-30",
"x-method": "derived",
"x-generator": "derive-json-schema.py",
"x-source": "openapi/_original/e2a-dev-api-openapi.yml#/components/schemas/ReplyRequest",
"additionalProperties": false,
"properties": {
"attachments": {
"description": "File attachments (base64 in each item's data). Limits: at most 10 attachments, each ≤ 10 MiB decoded, and ≤ 25 MiB decoded combined. Exceeding the count → 400 invalid_request; exceeding a size → 413 payload_too_large.",
"items": {
"$ref": "#/$defs/Attachment"
},
"type": "array"
},
"bcc": {
"description": "Additional Bcc recipients. The final message is limited to 50 recipients across to, cc, and bcc combined. Each recipient string (display name + address combined) is limited to 320 characters. The address itself must also fit SMTP's mailbox octet limits — local part at most 64 octets and the whole addr-spec at most 254 octets, counted in UTF-8 BYTES rather than characters — or the request is rejected with 400 invalid_recipient. A long plus-addressed local part is the usual way to exceed this.",
"items": {
"maxLength": 320,
"type": "string"
},
"type": "array"
},
"cc": {
"description": "Additional Cc recipients. The final message is limited to 50 recipients across to, cc, and bcc combined. Each recipient string (display name + address combined) is limited to 320 characters. The address itself must also fit SMTP's mailbox octet limits — local part at most 64 octets and the whole addr-spec at most 254 octets, counted in UTF-8 BYTES rather than characters — or the request is rejected with 400 invalid_recipient. A long plus-addressed local part is the usual way to exceed this.",
"items": {
"maxLength": 320,
"type": "string"
},
"type": "array"
},
"conversation_id": {
"description": "Caller-assigned application conversation/grouping id override. This value is independent of email thread topology, which is derived from the referenced message. At most 200 characters — deliberately the same cap as the webhook conversation_ids filter-value limit and the message-list conversation_id filter limit (both 200), so an accepted conversation_id is never too long to filter by. Must not contain CR or LF.",
"maxLength": 200,
"type": "string"
},
"html": {
"maxLength": 1048576,
"type": "string"
},
"quote_history": {
"description": "Beta: when true, the server appends the referenced message as mail-client-style quoted history beneath the reply body — an 'On <date>, <sender> wrote:' attribution line followed by the original text ('>'-prefixed) and, when an html body is supplied, the original HTML in a blockquote. Composition happens at accept time, so a held reply shows the reviewer the final quoted content. Only the body parts the caller supplies are quoted (a text-only reply stays text-only). Defaults to false (the body is sent exactly as provided). This field may change before it is declared stable.",
"type": "boolean",
"x-stability-level": "beta"
},
"reply_all": {
"type": "boolean"
},
"reply_to": {
"description": "Sets the Reply-To header — where replies to this message are directed. Either a single RFC 5322 address (optionally with a display name, e.g. \"Support <support@acme.com>\") or an array of up to 5 such addresses to direct replies to several destinations. Each address string is at most 320 characters (display name + address combined), and each address must fit SMTP's mailbox octet limits (local part at most 64 octets, whole addr-spec at most 254 octets, counted in UTF-8 bytes) — a violation is 400 invalid_request. Defaults to the sending agent's own address.",
"oneOf": [
{
"maxLength": 320,
"type": "string"
},
{
"items": {
"maxLength": 320,
"type": "string"
},
"maxItems": 5,
"type": "array"
}
]
},
"send_at": {
"description": "Beta: scheduled sending may change before it is declared stable. Optional scheduled-send time (RFC 3339 with a UTC offset). When set to a future instant the reply is accepted immediately and returns status=scheduled; it is submitted at approximately this time (\"not before\", accurate to the scheduler poll interval). A value at or before now sends immediately. Must be no more than 90 days ahead (over → 400 invalid_request). A future send_at whose only recipient is the sending agent's own address returns 400 invalid_request because self-delivery is an immediate loopback with no scheduled arm — this holds even when the reply would otherwise be held for review. Scheduling survives a review hold: if held, send_at is preserved on the pending_review message (surfaced as scheduled_at) and re-armed on approval — submitted at send_at if still future, or immediately if it has already passed. Moving the message to trash before provider submission starts prevents submission; if submission already has a fresh lease, delete returns 409 send_in_progress. Restoring before send_at re-arms it; restoring at or after send_at returns it live with delivery_status=failed and leaves the send canceled.",
"format": "date-time",
"type": "string",
"x-stability-level": "beta"
},
"text": {
"maxLength": 1048576,
"type": "string"
},
"unsubscribe": {
"$ref": "#/$defs/UnsubscribeOptions",
"description": "Beta: opts this message into e2a-managed unsubscribe handling. This field may change before it is declared stable.",
"x-stability-level": "beta"
}
},
"required": [
"text"
],
"type": "object",
"$defs": {
"Attachment": {
"additionalProperties": false,
"properties": {
"content_type": {
"type": "string"
},
"data": {
"description": "Base64-encoded file content. Each attachment must be ≤ 10 MiB decoded; a message may carry at most 10 attachments totaling ≤ 25 MiB decoded.",
"type": "string"
},
"filename": {
"description": "Attachment filename. Maximum 1024 UTF-8 bytes; longer names are rejected as invalid_attachment.",
"type": "string"
}
},
"required": [
"filename",
"content_type",
"data"
],
"type": "object"
},
"UnsubscribeOptions": {
"additionalProperties": false,
"description": "Beta: per-message opt-in to e2a-managed unsubscribe handling. This schema may change before it is declared stable.",
"properties": {
"mode": {
"description": "Beta: managed requests e2a-hosted unsubscribe handling. This option may change before it is declared stable.",
"enum": [
"managed"
],
"type": "string"
}
},
"required": [
"mode"
],
"type": "object",
"x-stability-level": "beta"
}
}
}
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