> ## Documentation Index > Fetch the complete documentation index at: https://docs.yorlet.com/llms.txt > Use this file to discover all available pages before exploring further. # Create a letter > Create a letter from a template or content blocks. Set `auto_send` to print and post immediately. ## OpenAPI ````yaml openapi-core.json POST /v1/letters openapi: 3.1.0 info: title: Yorlet Core API description: Core platform APIs including buildings, customers, units, and tasks. version: 1.0.0 servers: - url: https://api.yorlet.com description: Production - url: https://api.yorlet.io description: Sandbox security: [] paths: /v1/letters: post: tags: - Letters summary: Create a letter description: >- Create a letter from a template or content blocks. Set `auto_send` to print and post immediately. operationId: letters_create requestBody: content: application/json: schema: type: object properties: address_position: type: string enum: - left - right description: >- Which side of page 1 the recipient address window is printed on. auto_send: type: boolean default: false description: >- If true, the letter is printed and posted immediately after creation. blocks: type: array items: oneOf: - type: object properties: type: type: string enum: - heading content: type: string minLength: 1 description: >- Heading text. Supports the same merge fields as text blocks. required: - type - content - type: object properties: type: type: string enum: - signature file: type: - string - 'null' description: >- File ID of a signature image. When omitted, `name` is printed in a signature style. name: type: - string - 'null' description: >- Name printed under the signature. Defaults to the account name. required: - type - type: object properties: type: type: string enum: - text content: type: string minLength: 1 description: >- Body text. Supports merge fields such as `{{customer.name}}` and `{{owner.address}}`. required: - type - content description: >- Content blocks. Required when `template` is omitted; otherwise copied from the template. delivery_product: type: string enum: - standard - premium default: standard description: Postage product used when the letter is sent. name: type: string description: A name for this letter. Defaults to the template name. recipient: type: object properties: customer: type: string description: The customer ID. Required when `type` is `customer`. owner: type: string description: The owner ID. Required when `type` is `owner`. type: type: string enum: - customer - owner description: Who the letter is addressed to. description: Who the letter is addressed to. required: - type template: type: string description: The ID of a letter template to copy content from. variables: type: object additionalProperties: type: - string - 'null' description: >- Values for the template custom variables, keyed by variable key. required: - recipient responses: '200': description: Returns the letter object if the request succeeded. content: application/json: schema: type: object properties: id: type: string description: Unique identifier for the object. created: type: number description: >- Time at which the object was created. Measured in seconds since the Unix epoch. account: type: string description: >- The account that the object belongs to. Only returned if the request is made with a valid Yorlet-Context header. deleted: type: boolean default: false description: Only returned if the object has been deleted. object: type: string enum: - letter address_position: type: string enum: - left - right description: >- Which side of page 1 the recipient address window is printed on. blocks: type: array items: oneOf: - type: object properties: type: type: string enum: - heading content: type: string minLength: 1 description: >- Heading text. Supports the same merge fields as text blocks. required: - type - content - type: object properties: type: type: string enum: - signature file: type: - string - 'null' description: >- File ID of a signature image. When omitted, `name` is printed in a signature style. name: type: - string - 'null' description: >- Name printed under the signature. Defaults to the account name. required: - type - type: object properties: type: type: string enum: - text content: type: string minLength: 1 description: >- Body text. Supports merge fields such as `{{customer.name}}` and `{{owner.address}}`. required: - type - content description: >- Content blocks that will be printed. Snapshotted from the template when one is used. customer: anyOf: - type: string - type: object additionalProperties: {} - type: 'null' description: >- The customer this letter is addressed to, when `recipient_type` is `customer`. delivery_error: type: - string - 'null' description: Why sending failed, if `status` is `failed`. delivery_product: type: string enum: - standard - premium description: Postage product used when the letter is sent. name: type: - string - 'null' description: A name for this letter. Defaults to the template name. owner: anyOf: - type: string - type: object additionalProperties: {} - type: 'null' description: >- The owner this letter is addressed to, when `recipient_type` is `owner`. page_count: type: - integer - 'null' description: >- Number of PDF pages in the letter, set when it is sent. Extra pages beyond the first are billed separately. recipient_type: type: string enum: - customer - owner description: Who the letter is addressed to. sent_at: type: - number - 'null' description: >- Time at which the letter was submitted to for printing. Measured in seconds since the Unix epoch. status: type: string enum: - draft - sending - sent - canceled - failed description: The current status of the letter. template: anyOf: - type: string - type: object additionalProperties: {} - type: 'null' description: The letter template this letter was created from, if any. tracking_number: type: - string - 'null' description: Postal tracking number, when one is available. variables: type: object additionalProperties: type: - string - 'null' description: >- Values for the template custom variables, keyed by variable key. required: - id - created - object - address_position - blocks - customer - delivery_error - delivery_product - name - owner - page_count - recipient_type - sent_at - status - template - tracking_number - variables security: - ApiKeyAuth: [] components: securitySchemes: ApiKeyAuth: type: apiKey in: header name: Authorization description: API Key authentication. Use "Bearer YOUR_API_KEY". ````