---
title: "Changes to Send Windowed Letter"
method: POST
path: "/send/windowedletter"
---

# Changes to Send Windowed Letter

`POST /send/windowedletter`

> Every recorded change to this operation, newest first.

## Timeline

Changed in 13 of 51 revisions.

- **2026-10-19** `c403fbf3dc0f`: 1 info
- **2026-10-19** `bbe02ffe74f3`: 1 info
- **2026-10-18** `c10cfeb34552`: 1 warning
- **2026-10-17** `10023a95b079`: 1 info
- **2026-10-15** `4e41e9041848`: 1 warning, 1 info
- **2026-10-09** `9b6aa91faff7`: 1 info
- **2026-10-09** `c76fc453c7ca`: 1 warning
- **2026-10-07** `aaf5a075a328`: 1 info
- **2026-10-03** `1c7f08ab8dcd`: 1 warning, 4 info
- **2026-10-03** `91e51cdec675`: 13 info
- **2026-10-01** `02de08ab2a47`: 1 warning
- **2026-08-20** `4f2a64d375d2`: 2 info
- **2026-07-02** `7d3c46abd5ee`: 1 info

## Changes

- **2026-10-19** `c403fbf3dc0f`: 1 info
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/email_lookup`
- **2026-10-19** `bbe02ffe74f3`: 1 info
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/absentee_address` to the response with the `200` status
- **2026-10-18** `c10cfeb34552`: 1 warning
  - removed the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/absentee_address` from the response with the `200` status
- **2026-10-17** `10023a95b079`: 1 info
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/absentee_address` to the response with the `200` status
- **2026-10-15** `4e41e9041848`: 1 warning, 1 info
  - removed the request property `allOf[#/components/schemas/send-mailer-base]/send_standard_mail`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/postage_class`
- **2026-10-09** `9b6aa91faff7`: 1 info
  - added the new optional request property `allOf[subschema #2]/creative_id`
- **2026-10-09** `c76fc453c7ca`: 1 warning
  - removed the request property `allOf[subschema #2]/creative_id`
- **2026-10-07** `aaf5a075a328`: 1 info
  - added the new optional request property `allOf[subschema #2]/creative_id`
- **2026-10-03** `1c7f08ab8dcd`: 1 warning, 4 info
  - removed the request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/absentee_street`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/absentee_address`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/absentee_city`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/absentee_postal_code`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/absentee_province`
- **2026-10-03** `91e51cdec675`: 13 info
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/absentee_street`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/custom10`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/custom5`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/custom6`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/custom7`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/custom8`
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/recipients/items/custom9`
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/custom10` to the response with the `200` status
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/custom5` to the response with the `200` status
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/custom6` to the response with the `200` status
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/custom7` to the response with the `200` status
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/custom8` to the response with the `200` status
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/recipients/items/custom9` to the response with the `200` status
- **2026-10-01** `02de08ab2a47`: 1 warning
  - added the new `postcard6x9` enum value to the `oneOf[subschema #1: Send Mailer Order Submitted Response]/type` response property for the response status `200`
- **2026-08-20** `4f2a64d375d2`: 2 info
  - added the new optional request property `allOf[#/components/schemas/send-mailer-base]/metadata`
  - added the optional property `oneOf[subschema #1: Send Mailer Order Submitted Response]/metadata` to the response with the `200` status
- **2026-07-02** `7d3c46abd5ee`: 1 info
  - endpoint added

---

[Operation](https://skmtc.dev/thanks-io/apis/thanks-io-api/docs/send/windowedletter/post.md) · [API](https://skmtc.dev/thanks-io/apis/thanks-io-api.md) · [Page](https://skmtc.dev/thanks-io/apis/thanks-io-api/changes/send/windowedletter/post)