> ## Documentation Index > Fetch the complete documentation index at: https://docs.sendkit.dev/llms.txt > Use this file to discover all available pages before exploring further. # Send email > Send a transactional email to a recipient. You can provide the email content directly with `html`/`text`, or reference a published template by ID. When using a template, the `from`, `subject`, `html`, `text`, and `reply_to` fields are optional and will be resolved from the template if not provided. The `from` address must belong to a verified domain in your account. ## OpenAPI ````yaml POST /emails openapi: 3.1.0 info: title: SendKit API description: The SendKit API allows you to send transactional emails programmatically. version: 1.0.0 servers: - url: https://api.sendkit.dev security: - bearerAuth: [] paths: /emails: post: tags: - Emails summary: Send an email description: >- Send a transactional email to a recipient. You can provide the email content directly with `html`/`text`, or reference a published template by ID. When using a template, the `from`, `subject`, `html`, `text`, and `reply_to` fields are optional and will be resolved from the template if not provided. The `from` address must belong to a verified domain in your account. operationId: sendEmail requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SendEmailRequest' responses: '202': description: Email accepted for delivery content: application/json: schema: $ref: '#/components/schemas/SendEmailResponse' '401': description: Unauthorized — missing or invalid API key content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: name: validation_error message: Invalid API key. '422': description: Validation error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: name: validation_error message: The from address domain is not verified. '429': description: Rate limit exceeded content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: name: rate_limit_exceeded message: Rate limit exceeded. Please retry after 30 seconds. components: schemas: SendEmailRequest: type: object required: - to properties: from: type: string description: >- Sender email address. Required unless a template is provided (in which case, the template's sender is used as default). Must belong to a verified domain. example: Your Name to: oneOf: - type: string description: A single recipient email address or "Name " format. - type: array items: type: string minItems: 1 maxItems: 50 description: An array of recipient email addresses or "Name " format. description: >- Recipient email address(es). Accepts a single email string or an array of up to 50 emails. Supports display name format (e.g. "Bob "). example: user@example.com subject: type: string maxLength: 998 description: >- Email subject line. Required unless a template is provided. Maximum 998 characters. example: Welcome to SendKit html: type: string description: >- HTML body of the email. Required if `text` is not provided and no template is used. example:

Hello!

Welcome aboard.

text: type: string description: >- Plain text body of the email. Required if `html` is not provided and no template is used. example: Hello! Welcome aboard. cc: type: array items: type: string description: >- Carbon copy recipients. Supports display name format (e.g. "Name "). example: - cc@example.com bcc: type: array items: type: string description: >- Blind carbon copy recipients. Supports display name format (e.g. "Name "). example: - bcc@example.com reply_to: type: array items: type: string description: >- Reply-to email addresses. Supports display name format (e.g. "Name "). example: - support@yourdomain.com headers: type: object additionalProperties: type: string description: Custom email headers as key-value pairs. example: X-Custom-Header: value tags: type: array items: $ref: '#/components/schemas/Tag' description: Metadata tags as key-value pairs. scheduled_at: type: string format: date-time description: >- Schedule the email for future delivery. Must be a future ISO 8601 timestamp. example: '2026-03-05 10:30:00' attachments: type: array maxItems: 10 items: $ref: '#/components/schemas/Attachment' description: File attachments. Maximum 10 per email. template: type: - object - 'null' description: >- Use a published template instead of providing html/text directly. When provided, the template's content, subject, and sender are used as defaults. Any explicitly provided fields (from, subject, html, text, reply_to) will override the template values. properties: id: type: string format: uuid description: >- The template ID. Must be a published template belonging to your account. example: 550e8400-e29b-41d4-a716-446655440000 variables: type: - object - 'null' additionalProperties: type: string description: >- Key-value pairs to replace {{VARIABLE}} placeholders in the template. example: FIRST_NAME: John COMPANY: Acme Inc required: - id SendEmailResponse: oneOf: - type: object description: Returned when sending to a single recipient. properties: id: type: string format: uuid description: Unique identifier of the created email. example: 550e8400-e29b-41d4-a716-446655440000 - type: object description: Returned when sending to multiple recipients. properties: data: type: array items: type: object properties: id: type: string format: uuid description: Unique identifier of the created email. description: Array of created emails, one per recipient. ErrorResponse: type: object properties: name: type: string description: Error type identifier. example: validation_error message: type: string description: Human-readable error message. example: The from address domain is not verified. Tag: type: object required: - name - value properties: name: type: string maxLength: 256 description: Tag name. example: campaign value: type: string maxLength: 256 description: Tag value. example: welcome Attachment: type: object required: - filename - content properties: filename: type: string maxLength: 255 description: Name of the file. example: invoice.pdf content: type: string description: Base64-encoded file content. example: JVBERi0xLjQKJeLj... content_type: type: string maxLength: 255 description: >- MIME type of the file. If not provided, it will be inferred from the filename. example: application/pdf securitySchemes: bearerAuth: type: http scheme: bearer description: >- API key from your SendKit dashboard. Pass it as a Bearer token in the Authorization header. ````