> ## Documentation Index > Fetch the complete documentation index at: https://cool.computer/docs/llms.txt > Use this file to discover all available pages before exploring further. # Reply to computer email > Replies to one stored email from the computer's stable inbox address. The server resolves the recipient, subject, and thread from the stored message; callers provide only the approved reply content. Send an Idempotency-Key when a network failure might cause a retry. ## OpenAPI ````yaml https://www.cool.computer/openapi.json post /api/computers/{id}/emails/{emailID}/reply openapi: 3.1.0 info: title: Cool Computers API version: 1.0.0 description: >- Create and operate reachable Linux computers. Each computer keeps a stable name.cool.computer address, persistent files, and agent-ready command execution. REST requests use UTC-aligned one-minute limits: 600 requests per account identified by a recognized valid account bearer credential, a separate 600-request budget per computer-scoped credential, or 60 requests per source IP otherwise. Read-only GETs answered from API state spend a separate read budget reported as account-read or computer-read, so status polling cannot exhaust the budget that protects work and mutations. To bound authentication-provider traffic, at most 60 first-seen bearer values are checked per source IP in a minute; recognized valid credentials use their account or computer policy. Successful bearer authentication is reused for at most five seconds; transient provider failures are not cached. Non-exempt API responses include the structured RateLimit and RateLimit-Policy fields; request admission 429 responses use code api_request_rate_exceeded and also include Retry-After. Health, OpenAPI, webhooks, callbacks, SSE, and WebSocket endpoints are exempt from the REST request budget. Authenticated SSE connection attempts remain subject to the authentication safeguards and can receive the same typed 429 response. servers: - url: https://api.cool.computer description: Canonical API origin security: [] tags: - name: Authentication description: Obtain and manage bearer credentials. - name: Billing description: Inspect and manage the account's no-card trial or Pro plan. - name: Computers description: Create, inspect, and delete resident computers. - name: Execution description: Run commands on a computer. - name: Files description: Read and change a computer's persistent files. - name: Publishing description: >- Publish files to a computer's URL as immutable releases, with no VM. To show something, publish the files; to run something, use the computer (exec, terminal, services), which gets Linux on first use. - name: Services description: >- Manage processes and select the HTTP port exposed at a computer's stable address. - name: Email description: Read and send mail through a computer's inbox. - name: Network description: Control a computer's public visibility and outbound network policy. - name: Sharing description: Invite people to use a computer without granting owner controls. - name: Public description: Unauthenticated discovery endpoints. externalDocs: description: Cool Computers agent registration guide url: https://www.cool.computer/auth.md paths: /api/computers/{id}/emails/{emailID}/reply: post: tags: - Email summary: Reply to computer email description: >- Replies to one stored email from the computer's stable inbox address. The server resolves the recipient, subject, and thread from the stored message; callers provide only the approved reply content. Send an Idempotency-Key when a network failure might cause a retry. operationId: replyToComputerEmail parameters: - $ref: '#/components/parameters/ComputerID' - $ref: '#/components/parameters/EmailID' - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/EmailReplyRequest' responses: '201': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Safe delivery metadata for the stored outbound reply. content: application/json: schema: $ref: '#/components/schemas/EmailReplyResult' '400': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Bad Request. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '401': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Unauthorized. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '402': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- Payment Required. The trial expired or Pro is inactive; inspect the problem code and resolution. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '403': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Forbidden. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '404': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Not Found. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '409': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- The idempotency key is in progress, has an unknown outcome, or was used for a different request. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '413': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Payload Too Large. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '429': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' Retry-After: $ref: '#/components/headers/Retry-After' description: >- Too Many Requests. If the problem code is api_request_rate_exceeded, wait for Retry-After seconds; other problem codes describe a separate limit. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '500': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Internal Server Error. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '503': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Service Unavailable. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' default: headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- A machine-readable API error with a stable code and recovery instruction. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' security: - bearerAuth: [] components: parameters: ComputerID: name: id in: path required: true description: Stable public computer identifier. schema: type: string minLength: 1 example: cmp_123 EmailID: name: emailID in: path required: true description: Email identifier returned by the inbox list operation. schema: type: string minLength: 1 example: eml_123 IdempotencyKey: name: Idempotency-Key in: header required: false description: >- A caller-generated key for safely retrying this side effect. The server retains the key and response for 24 hours. Reusing it with the same request replays the original response; reusing it with different input returns 409. schema: type: string minLength: 1 maxLength: 128 pattern: ^[!-~]+$ example: req_01J6M6Y9TF9Q9QF6M1ZP8K4R2A schemas: EmailReplyRequest: type: object additionalProperties: false anyOf: - required: - text properties: text: pattern: \S - required: - html properties: html: pattern: \S properties: text: type: string description: >- Plain-text reply body. The text and HTML bodies together are limited to 1 MiB. html: type: string description: >- HTML reply body. The text and HTML bodies together are limited to 1 MiB. EmailReplyResult: type: object additionalProperties: false required: - id - status - created_at properties: id: type: string status: type: string enum: - sent created_at: type: string format: date-time Problem: type: object additionalProperties: false required: - type - title - status - code - detail - resolution properties: type: type: string format: uri title: type: string status: type: integer minimum: 400 maximum: 599 code: type: string pattern: ^[a-z0-9_]+$ detail: type: string resolution: type: string context: type: object additionalProperties: true headers: RateLimit: description: >- The applied policy name, requests remaining after this request, and whole seconds until the current UTC-aligned window resets. schema: type: string pattern: >- ^"(account|account-read|computer|computer-read|source)";r=[0-9]+;t=([1-9]|[1-5][0-9]|60)$ examples: - '"account";r=599;t=42' - '"computer-read";r=598;t=42' RateLimit-Policy: description: >- The selected policy name, quota, and window in seconds. Valid account credentials use account or account-read with q=600, computer credentials use computer or computer-read with q=600, and unauthenticated or unrecognized requests use source with q=60 for their source IP. schema: type: string pattern: >- ^("(account|account-read|computer|computer-read)";q=600|"source";q=60);w=60$ examples: - '"account";q=600;w=60' - '"computer-read";q=600;w=60' Retry-After: description: >- Whole seconds to wait after an api_request_rate_exceeded response before retrying. Other 429 problem codes describe separate resource or provider limits and do not inherit this retry value. schema: type: integer minimum: 1 maximum: 60 examples: - 42 securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: WorkOS user or agent access token, or Cool Computers API key description: >- A Cool Computers API key, user access token, or claimed agent access token in the Authorization header. Follow https://www.cool.computer/auth.md for agent registration and https://www.cool.computer/authentication.md for direct user credentials. ````