> ## Documentation Index > Fetch the complete documentation index at: https://sendmux.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Get mailbox API session > Returns mailbox API capabilities, resource state tokens, limits, and disabled feature flags for the authenticated mailbox. ## OpenAPI ````yaml /openapi-app.json get /mailbox/session openapi: 3.1.0 info: description: Programmatic access to your Sendmux email infrastructure. title: Sendmux API version: 1.0.0 servers: - description: API v1 url: https://app.sendmux.ai/api/v1 security: - bearerAuth: [] paths: /mailbox/session: get: tags: - Mailbox API summary: Get mailbox API session description: >- Returns mailbox API capabilities, resource state tokens, limits, and disabled feature flags for the authenticated mailbox. operationId: mailboxGetSession parameters: - in: header name: If-None-Match required: false schema: description: Weak ETag from a previous response. Returns 304 when unchanged. type: string - description: >- Mailbox public ID to target when the credential grants access to more than one mailbox. Omit when the credential is scoped to exactly one mailbox. in: query name: mailbox_id required: false schema: type: string responses: '200': content: application/json: schema: $ref: '#/components/schemas/MailboxSessionResponse' description: Mailbox API session '304': description: Not modified '401': content: application/json: schema: $ref: '#/components/schemas/ApiError' description: Authentication required '403': content: application/json: schema: $ref: '#/components/schemas/ApiError' description: Mailbox API key required '503': content: application/json: schema: $ref: '#/components/schemas/ApiError' description: Mailbox service unavailable security: - bearerAuth: [] components: schemas: MailboxSessionResponse: allOf: - $ref: '#/components/schemas/SuccessEnvelope' - properties: data: $ref: '#/components/schemas/MailboxSession' meta: $ref: '#/components/schemas/ResponseMeta' required: - data type: object unevaluatedProperties: false ApiError: additionalProperties: false properties: error: additionalProperties: false properties: code: description: Machine-readable error code enum: - invalid_parameter - missing_parameter - authentication_required - insufficient_permissions - not_found - conflict - limit_exceeded - idempotency_conflict - payload_too_large - validation_error - rate_limit_exceeded - service_unavailable - internal_error example: invalid_parameter type: string doc_url: description: Link to relevant documentation type: string errors: description: >- Accumulated per-field issues for validation errors. Only present on 400/422 responses. items: $ref: '#/components/schemas/ApiErrorDetail' type: array message: description: Human-readable error description type: string param: description: The parameter that caused the error type: string retryable: description: >- Whether the caller may safely retry this request. 4xx are typically false (except 429); 5xx are typically true. example: false type: boolean required: - code - message - retryable type: object meta: additionalProperties: false properties: request_id: example: req_clxxxxxxxxxxxxxxxxxxxxxxxxx type: string required: - request_id type: object ok: enum: - false type: boolean required: - ok - error - meta type: object SuccessEnvelope: properties: meta: additionalProperties: {} properties: {} type: object ok: enum: - true type: boolean required: - ok - meta type: object MailboxSession: additionalProperties: false properties: capabilities: additionalProperties: false properties: attachments: additionalProperties: false properties: download: type: boolean metadata: type: boolean parsing: type: boolean range_download: type: boolean send_with_uploaded_blob: type: boolean upload: type: boolean required: - upload - download - range_download - metadata - parsing - send_with_uploaded_blob type: object folders: additionalProperties: false properties: changes: type: boolean create: type: boolean delete: type: boolean detail: type: boolean list: type: boolean query_changes: type: boolean update: type: boolean required: - list - detail - create - update - delete - changes - query_changes type: object identities: additionalProperties: false properties: changes: type: boolean create: type: boolean delete: type: boolean list: type: boolean update: type: boolean required: - list - changes - create - update - delete type: object messages: additionalProperties: false properties: batch_get: type: boolean batch_update: type: boolean changes: type: boolean clean_content: type: boolean count: type: boolean delete: type: boolean detail: type: boolean keywords: type: boolean list: type: boolean permanent_delete: type: boolean query_changes: type: boolean raw_body: type: boolean search_snippets: type: boolean update_fields: items: enum: - seen - flagged - keywords type: string type: array required: - list - detail - raw_body - clean_content - batch_get - count - search_snippets - changes - query_changes - update_fields - keywords - batch_update - delete - permanent_delete type: object quotas: additionalProperties: false properties: changes: type: boolean list: type: boolean update: type: boolean usage: type: boolean required: - list - usage - changes - update type: object submissions: additionalProperties: false properties: changes: type: boolean detail: type: boolean list: type: boolean send: type: boolean required: - list - detail - changes - send type: object sync: additionalProperties: false properties: query_changes: items: enum: - messages - folders type: string type: array typed_changes: type: boolean types: items: enum: - messages - folders - threads - submissions - identities - quotas type: string type: array required: - typed_changes - types - query_changes type: object threads: additionalProperties: false properties: changes: type: boolean clean_content: type: boolean detail: type: boolean list: type: boolean messages: type: boolean required: - list - detail - messages - clean_content - changes type: object required: - messages - threads - folders - submissions - identities - quotas - attachments - sync type: object endpoints: additionalProperties: false properties: folders: items: type: string type: array mailbox: items: type: string type: array messages: items: type: string type: array submissions: items: type: string type: array sync: items: type: string type: array threads: items: type: string type: array usage: items: type: string type: array required: - mailbox - messages - threads - folders - submissions - usage - sync type: object gated: additionalProperties: false description: >- Flags are true when a feature is intentionally unavailable through the mailbox API. properties: attachment_parsing: type: boolean blob_copy: type: boolean blob_lookup: type: boolean events: type: boolean filter_script_writes: type: boolean identity_mutation: type: boolean message_copy: type: boolean message_import: type: boolean message_parse: type: boolean quota_mutation: type: boolean raw_protocol: type: boolean vacation_response: type: boolean required: - identity_mutation - quota_mutation - vacation_response - filter_script_writes - events - raw_protocol - attachment_parsing - message_copy - message_import - message_parse - blob_lookup - blob_copy type: object limits: additionalProperties: false properties: attachment_upload_bytes_max: type: integer batch_ids_max: type: integer body_chars_max: type: integer changes_limit_max: type: integer inline_attachment_bytes_max: type: integer keywords_per_update_max: type: integer list_limit_max: type: integer message_body_chars_default: type: integer outbound_raw_message_bytes_max: type: integer thread_body_chars_default: type: integer required: - list_limit_max - changes_limit_max - batch_ids_max - message_body_chars_default - thread_body_chars_default - body_chars_max - inline_attachment_bytes_max - attachment_upload_bytes_max - outbound_raw_message_bytes_max - keywords_per_update_max type: object mailbox: additionalProperties: false properties: display_name: type: - string - 'null' email: example: agent@example.com format: email type: string id: description: Mailbox public ID example: mbx_clxxxxxxxxxxxxxxxxxxxxxxxxx type: string required: - id - email - display_name type: object states: additionalProperties: false properties: folders: type: string identities: type: string messages: type: string quotas: type: string submissions: type: string threads: type: string required: - messages - folders - threads - submissions - identities - quotas type: object required: - mailbox - states - capabilities - limits - gated - endpoints type: object ResponseMeta: additionalProperties: false properties: request_id: example: req_clxxxxxxxxxxxxxxxxxxxxxxxxx type: string required: - request_id type: object ApiErrorDetail: additionalProperties: false properties: code: description: >- Machine-readable issue code from the validator (e.g. zod issue code). example: invalid_string type: string field: description: Dot-path of the offending request field. example: recipient.email type: string message: description: Human-readable issue description. type: string required: - field - code - message type: object securitySchemes: bearerAuth: bearerFormat: API Key description: >- Sendmux API key. Use a root API key for Management API routes, or a mailbox credential for Mailbox API routes. Obtain keys from the dashboard under API Keys. scheme: bearer type: http ````