> ## Documentation Index > Fetch the complete documentation index at: https://docs.trylath.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Every Lath operation is POST https://platform.trylath.com/, with a JSON body and `Authorization: Bearer `. `email.send` is POST /email/send. > Branch on `error.code`, never on `error.message`. Every refusal also carries `error.fix`, which names the next step. > Send an `Idempotency-Key` header on any operation that is not retry-safe, so a retry cannot run it twice. > A `lath_test_` key emails only the account's own members and sends no SMS; a `lath_live_` key reaches real recipients and is billed. > The OpenAPI document, generated from the same registry as the routes, is at https://platform.trylath.com/openapi.json. # email.send > Sends one transactional email to one recipient, from the project's default sender, either from a named template with variables or from inline subject and body. Asks the audience policy first: a suppressed address is recorded as suppressed, not sent. Returns the message id and its status. ## OpenAPI ````yaml /api-reference/openapi.json post /email/send openapi: 3.1.0 info: title: Lath API version: 0.1.0 description: >- Every operation is one POST. The same set is reachable over MCP, the SDK and the CLI; nothing is dashboard-only. servers: - url: https://platform.trylath.com description: This deployment security: [] paths: /email/send: post: tags: - email summary: email.send description: >- Sends one transactional email to one recipient, from the project's default sender, either from a named template with variables or from inline subject and body. Asks the audience policy first: a suppressed address is recorded as suppressed, not sent. Returns the message id and its status. operationId: email.send parameters: - name: Idempotency-Key in: header required: false schema: type: string description: >- Replays the stored response for the same key and input; refuses different input. requestBody: required: true content: application/json: schema: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: to: type: string format: email pattern: >- ^(?!\.)(?!.*\.\.)([A-Za-z0-9_'+\-\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$ description: One recipient template: description: A template name; provide variables with it type: string minLength: 1 maxLength: 120 locale: description: >- Send the template's variant for this language, falling back to the broader language and then the default. Omit to use the recipient's own locale if one is recorded. type: string maxLength: 20 variables: type: object propertyNames: type: string pattern: ^[A-Za-z_][A-Za-z0-9_]*$ additionalProperties: {} subject: description: >- Inline send: the subject (with template, overrides the template's subject) type: string minLength: 1 maxLength: 998 html: description: 'Inline send: the HTML body' type: string maxLength: 200000 text: description: >- Inline send: the plain-text body; derived from html when omitted type: string maxLength: 100000 layout: default: brand description: >- Inline send only: wrap the HTML in the project's themed frame type: string enum: - brand - none from: description: >- The project's default sender (omit) or any address on one of its verified domains type: string format: email pattern: >- ^(?!\.)(?!.*\.\.)([A-Za-z0-9_'+\-\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$ replyTo: type: string format: email pattern: >- ^(?!\.)(?!.*\.\.)([A-Za-z0-9_'+\-\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$ fromName: description: >- The name shown in the inbox beside the address. Defaults to the project's name; pass an empty string to send the bare address. type: string maxLength: 120 sendAfter: description: >- Hold the message until this moment; omit to send now. Until it is sent it can be stopped with email.message.cancel. type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:\.\d+)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$ metadata: description: >- Up to 20 key/values echoed on every webhook about this message type: object propertyNames: type: string maxLength: 40 additionalProperties: anyOf: - type: string maxLength: 500 - type: number - type: boolean attachments: description: >- Files to attach. Base64 content, at most 10 MB across all of them. maxItems: 10 type: array items: type: object properties: filename: type: string minLength: 1 maxLength: 200 contentType: default: application/octet-stream type: string maxLength: 200 pattern: >- ^[a-zA-Z0-9!#$&^_.+-]+\/[a-zA-Z0-9!#$&^_.+-]+(\s*;\s*[a-zA-Z0-9!#$&^_.+-]+=[^\r\n;]{1,80})*$ content: type: string format: base64 contentEncoding: base64 pattern: >- ^$|^(?:[0-9a-zA-Z+/]{4})*(?:(?:[0-9a-zA-Z+/]{2}==)|(?:[0-9a-zA-Z+/]{3}=))?$ description: The file's bytes, base64 encoded required: - filename - content additionalProperties: false required: - to additionalProperties: false responses: '200': description: '{ activityId, result }. activityId is empty for reads.' content: application/json: schema: type: object properties: activityId: type: string description: The activity this call created, or empty for a read. result: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: messageId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ status: type: string enum: - queued - suppressed attachments: type: array items: type: object properties: filename: type: string contentType: type: string sizeBytes: type: integer minimum: -9007199254740991 maximum: 9007199254740991 required: - filename - contentType - sizeBytes additionalProperties: {} to: type: string from: type: string fromName: type: - string - 'null' subject: type: - string - 'null' template: type: - string - 'null' templateVersion: anyOf: - type: integer minimum: -9007199254740991 maximum: 9007199254740991 - type: 'null' templateLocale: type: - string - 'null' sendAfter: anyOf: - type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:\.\d+)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$ - type: 'null' suppressed: type: object properties: reason: type: string detail: type: string required: - reason - detail additionalProperties: {} required: - messageId - status - attachments - to - from - fromName - subject - template - templateVersion - templateLocale - sendAfter additionalProperties: {} required: - activityId - result '400': description: invalid_input or invalid_json '401': description: unauthenticated '403': description: forbidden '404': description: not_found '409': description: 'conflict: idempotency_mismatch, email_taken, last_key' '413': description: body_too_large '429': description: rate_limited security: - bearer: [] components: securitySchemes: bearer: type: http scheme: bearer description: >- A Lath API key: lath_live_sk… or lath_test_sk… on a server, lath_live_pk… or lath_test_pk… in a browser. ````