> ## Documentation Index > Fetch the complete documentation index at: https://developer.paywint.com/llms.txt > Use this file to discover all available pages before exploring further. # Mail Check > Sends a physical check payment by mail to a specified payee on behalf of a platform user. This endpoint will: - Download and validate the check attachment (PDF only, max 7MB, up to 10 pages) - Calculate processing fees based on mail type and attachment pages - Deduct the total amount (payment + fees) from the user's wallet - Generate and mail a physical check to the payee's address - Create payment and check records for tracking Supported mail types include USPS First Class, USPS Certified, Overnight, and Two-Day delivery. Processing fees vary by mail type and include additional charges for attachment pages. ## OpenAPI ````yaml POST /api/platform/payment/mail-check/{user_id} openapi: 3.1.0 info: title: paywint version: 0.1.0 servers: - url: http://localhost:8001 - url: https://api.pw.wintpay.com - url: https://test.pw.wintpay.com - url: https://api.sandbox.paywint.com security: [] paths: /api/platform/payment/mail-check/{user_id}: post: tags: - Platform payment summary: Send Physical Check Payment description: >- Sends a physical check payment by mail to a specified payee on behalf of a platform user. This endpoint will: - Download and validate the check attachment (PDF only, max 7MB, up to 10 pages) - Calculate processing fees based on mail type and attachment pages - Deduct the total amount (payment + fees) from the user's wallet - Generate and mail a physical check to the payee's address - Create payment and check records for tracking Supported mail types include USPS First Class, USPS Certified, Overnight, and Two-Day delivery. Processing fees vary by mail type and include additional charges for attachment pages. operationId: mail_check_api_platform_payment_mail_check__user_id__post parameters: - name: user_id in: path required: true schema: type: string format: uuid description: Unique identifier (UUID) of the user who mails the check. title: User Id description: Unique identifier (UUID) of the user who mails the check. example: f47ac10b-****-****-****-0e02b2c3d479 - name: X-Platform-ID in: header required: true schema: type: string format: uuid description: >- Unique platform identifier (UUID). You receive this during onboarding. Must be sent with every API request. title: X-Platform-Id description: >- Unique platform identifier (UUID). You receive this during onboarding. Must be sent with every API request. - name: X-Signature in: header required: true schema: type: string description: >- HMAC-SHA256 request signature for authentication. Use your platform secret key to compute it as: `METHOD + PATH + QUERY + BODY_HASH`. title: X-Signature description: >- HMAC-SHA256 request signature for authentication. Use your platform secret key to compute it as: `METHOD + PATH + QUERY + BODY_HASH`. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ExternalCheckPaymentCreate' responses: '200': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/CommonResponse_ExternalCheckPaymentRead_' '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' components: schemas: ExternalCheckPaymentCreate: properties: payee_id: type: string format: uuid4 title: Payee Id description: >- Unique identifier (UUID) of the recipient who will receive the physical check. example: f47ac10b-****-****-****-0e02b2c3d479 amount: type: number minimum: 1 title: Amount description: Payment amount in USD. Must be at least $1.00. example: 150 payee_address_id: type: string format: uuid4 title: Payee Address Id description: >- UUID of the recipient's mailing address where the physical check will be sent. example: f47ac10b-****-****-****-0e02b2c3d479 invoice_no: anyOf: - type: string maxLength: 20 - type: 'null' title: Invoice No description: >- Invoice or reference number that will appear on the check for tracking purposes. example: INV-2024-001234 description: anyOf: - type: string maxLength: 255 - type: 'null' title: Description description: Optional memo or description that will appear on the check. example: Payment for consulting services mail_type: $ref: '#/components/schemas/CheckMailType' description: >- Delivery method for the physical check. Options: USPS_FIRST_CLASS (default), USPS_CERTIFIED, OVERNIGHT, TWO_DAY. Different mail types have different processing fees. default: USPS_FIRST_CLASS example: USPS_FIRST_CLASS payment_method: $ref: '#/components/schemas/ExternalCheckPaymentMethodRead' description: >- Payment source for the check amount and fees. Currently only WALLET is supported. default: WALLET example: WALLET remittance: anyOf: - items: $ref: '#/components/schemas/RemittanceAdvice' type: array - type: 'null' title: Remittance description: >- Optional list of remittance details to include with the check (maximum 50 items). Useful for invoice breakdowns or payment details. attachment_url: anyOf: - type: string - type: 'null' title: Attachment Url description: >- Optional HTTPS URL of a PDF document to attach to the check. Must be a valid PDF, maximum 7MB, up to 10 pages. Additional fees apply per page. example: https://example.com/documents/invoice.pdf type: object required: - payee_id - amount - payee_address_id title: ExternalCheckPaymentCreate CommonResponse_ExternalCheckPaymentRead_: properties: success: type: boolean title: Success description: Indicates whether the request was processed successfully. default: true example: true message: type: string title: Message description: >- A short, human-readable message describing the result of the request. default: Success example: Operation completed. data: anyOf: - $ref: '#/components/schemas/ExternalCheckPaymentRead' - type: 'null' description: The main response payload, if applicable queryGeneratedTime: anyOf: - type: number - type: 'null' title: Querygeneratedtime description: >- The Unix timestamp (in seconds) indicating when the response was generated. default: 1782303609.673092 example: 1718006400 type: object title: CommonResponse[ExternalCheckPaymentRead] HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' type: array title: Detail type: object title: HTTPValidationError CheckMailType: type: string enum: - USPS_FIRST_CLASS - USPS_CERTIFIED - TWO_DAY - OVERNIGHT title: CheckMailType ExternalCheckPaymentMethodRead: type: string enum: - WALLET title: ExternalCheckPaymentMethodRead RemittanceAdvice: properties: id: type: string maxLength: 50 minLength: 1 title: Id description: >- Reference identifier for this remittance item (e.g., invoice number, transaction ID). example: INV-001 date: type: string title: Date description: >- Date in MM-DD-YYYY format. Must be today or a future date (UTC timezone). example: 09-15-2025 amount: type: number minimum: 0 title: Amount description: Amount associated with this remittance item. example: 150 gross: anyOf: - type: number - type: 'null' title: Gross description: Gross amount for this remittance entry. example: 150 discount: anyOf: - type: number - type: 'null' title: Discount description: Discount associated with this remittance entry. example: 10 description: anyOf: - type: string - type: 'null' title: Description description: Optional description or note for this remittance item. example: Consulting services - September 2025 type: object required: - id - date - amount title: RemittanceAdvice ExternalCheckPaymentRead: properties: payment_id: anyOf: - type: string format: uuid - type: 'null' title: Payment Id description: Unique identifier (UUID) of the payment transaction. example: f47ac10b-****-****-****-0e02b2c3d479 transaction_id: anyOf: - type: integer - type: 'null' title: Transaction Id description: Integer ID of the payment example: 1501 payer_id: anyOf: - type: string format: uuid - type: 'null' title: Payer Id description: Unique identifier (UUID) of the user who initiated the payment. example: f47ac10b-****-****-****-0e02b2c3d479 payee_id: anyOf: - type: string format: uuid - type: 'null' title: Payee Id description: Unique identifier (UUID) of the recipient who received the payment example: f47ac10b-****-****-****-0e02b2c3d479 amount: anyOf: - type: number - type: 'null' title: Amount description: Total amount transferred in the transaction. example: 100 processing_fee: anyOf: - type: number - type: 'null' title: Processing Fee description: Processing fee charged on payment. example: 1.5 delivery_fee: anyOf: - type: number - type: 'null' title: Delivery Fee description: Delivery fee charged on payment. example: 0.5 invoice_no: anyOf: - type: string - type: 'null' title: Invoice No description: >- Invoice or transaction reference number for tracking and record-keeping purposes. example: INV-2024-001234 currency: anyOf: - type: string - type: 'null' title: Currency description: Three-letter ISO currency code for the transaction (e.g., USD). example: USD description: anyOf: - type: string - type: 'null' title: Description description: Optional note or description attached to the payment. example: June invoice for services created_at: anyOf: - type: string format: date-time - type: 'null' title: Created At description: Timestamp when the payment record was initially created. example: '2025-06-16T10:04:51.739761Z' payment_date: anyOf: - type: string format: date-time - type: 'null' title: Payment Date description: Timestamp when the payment was successfully processed or completed. example: '2025-06-16T10:13:16.749655Z' status: $ref: '#/components/schemas/PlatformPaymentStatus' description: The current status of the payment (e.g., success, failed, pending). example: success card_id: anyOf: - type: string format: uuid - type: 'null' title: Card Id description: UUID of the payer's card. example: f47ac10b-****-****-****-0e02b2c3d479 bank_id: anyOf: - type: string format: uuid - type: 'null' title: Bank Id description: UUID of the payer's bank account. example: f47ac10b-****-****-****-0e02b2c3d479 payee_card_id: anyOf: - type: string format: uuid - type: 'null' title: Payee Card Id description: UUID of the payee's card where funds are received. example: f47ac10b-****-****-****-0e02b2c3d479 payee_bank_id: anyOf: - type: string format: uuid - type: 'null' title: Payee Bank Id description: UUID of the payee's bank account where funds are received. example: f47ac10b-****-****-****-0e02b2c3d479 failure_reason: anyOf: - type: string - type: 'null' title: Failure Reason description: Explanation for why the payment failed, if applicable. example: Insufficient wallet balance payment_method: anyOf: - $ref: '#/components/schemas/ExternalCheckPaymentMethodRead' - type: 'null' description: The method used to send the payment (e.g., WALLET, CARD, ACH). example: WALLET receiving_method: anyOf: - $ref: '#/components/schemas/ExternalPaymentReceivingMethodRead' - type: 'null' description: >- The destination method where the payment was received (e.g., CHECK_MAIL, WALLET, CARD, ACH). example: CHECK_MAIL attachment_url: anyOf: - type: string - type: 'null' title: Attachment Url description: Optional URL of the attachment added with the check. example: >- https://paywint-bucket.s3.amazonaws.com/wallet/check-payments/23ec826b-54cd-4241-a855-ae038bbf568a/testing.pdf type: object title: ExternalCheckPaymentRead ValidationError: properties: loc: items: anyOf: - type: string - type: integer type: array title: Location msg: type: string title: Message type: type: string title: Error Type type: object required: - loc - msg - type title: ValidationError PlatformPaymentStatus: type: string enum: - requested - initiated - check_pending - processing - SETTLING - approved - success - failed - request_failed - rejected - declined - mailed - expired title: PlatformPaymentStatus ExternalPaymentReceivingMethodRead: type: string enum: - CHECK_MAIL title: ExternalPaymentReceivingMethodRead ````