---
title: "Update a newsletter"
method: PATCH
path: "/newsletters/{id}"
tags: ["Newsletters"]
---

# Update a newsletter

`PATCH /newsletters/{id}`

## Request

- Base URL: `https://shipmail.to/api/v1`
- URL: `https://shipmail.to/api/v1/newsletters/{id}`
- Auth: one of:
  - HTTP bearer
  - OAuth 2 (authorization code, authorization URL `https://shipmail.to/api/auth/oauth2/authorize`, token URL `https://shipmail.to/api/auth/oauth2/token`)

Update an editable draft newsletter or a scheduled newsletter whose send time is still in the future. Changing message content, presentation, or audience returns a scheduled newsletter to draft and clears scheduled_at; inspect the returned status, send a new test, and schedule again. Name, feed link, and send-window changes can keep the schedule and refresh its recipient snapshot. Sending and sent newsletters cannot be edited. The server applies an internal revision check and returns 409 if another save wins concurrently; fetch the latest newsletter before retrying.

## Path parameters

- `id` string, required

## Headers

- `X-Shipmail-Organization` string

## Request body

- UpdateNewsletterRequest
  - `audience_id` string
  - `sender_identity_id` string
  - `name` string
  - `subject` string
  - `preview_text` string, nullable
  - `body_html` string, nullable: Full HTML body. Stored as one custom_html block when blocks are not provided.
  - `body_text` string, nullable: Plain-text body. Becomes paragraph blocks when blocks are not provided. With blocks or body_html, sets the plain-text override.
  - `send_window_hours` integer
  - `archive_visibility` 'private' | 'public'
  - `feed_entry_url` string, uri, nullable: Optional http(s) Atom entry destination. Send null to clear it.
  - `styling_mode` 'styled' | 'plain': styled applies Shipmail's email theme. plain sends your HTML without injected styles, width, or centering, so the reader's email client styles it.
  - `track_engagement` boolean: Track opens and clicks for this newsletter. Omit to keep the current value. Returns 422 validation_error when open and click tracking is not available. Can only change while the newsletter is an editable draft or a future scheduled newsletter.
  - `add_utm_tags` boolean: Add UTM tags to the links of this newsletter. Omit to keep the current value. Adds utm_source=shipmail, utm_medium (email or feed) and utm_campaign (a slug of the subject) to the newsletter's http and https links. Links that already carry a utm_ parameter, links with a merge tag in the host, and Shipmail's own unsubscribe and archive links are left alone. The web archive is never tagged. Can only change while the newsletter is an editable draft or a future scheduled newsletter.
  - `blocks` NewsletterBlock[]: Preferred body format. Shipmail stores blocks and renders body_html and body_text from them. Rich prose fields accept bare text or sanitized inline HTML.
    - union: Structured newsletter block. paragraph.body, quote.body, callout.body, list items, and column bodies accept bare text or restricted inline HTML. Shipmail sanitizes these values when it stores the blocks and renders email-safe HTML and text.
      - object
        - `type` 'heading', required
        - `text` string, required: Heading text.
        - `level` 1 | 2 | 3
      - object
        - `type` 'paragraph', required
        - `body` string, required: Bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks and HTML entities for literal tag-like text.
      - object
        - `type` 'list', required
        - `ordered` boolean
        - `items` string[], required
      - object
        - `type` 'callout', required
        - `title` string, nullable: Optional callout title.
        - `body` string, required: Bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
        - `variant` 'accent' | 'info' | 'warning' | 'success'
      - object
        - `type` 'button', required
        - `label` string, required: Button label.
        - `url` string, required: Absolute http, https, or mailto URL.
        - `align` 'left' | 'center' | 'right': Horizontal alignment of the button.
      - object
        - `type` 'image', required
        - `url` string, uri, required: Hosted HTTPS image URL.
        - `alt` string, required: Image alt text.
        - `align` 'left' | 'center' | 'right': Horizontal alignment of the image and its caption.
        - `link_url` string, nullable: Optional absolute http, https, or mailto image link.
        - `caption` string, nullable: Optional image caption.
        - `caption_url` string, nullable: Optional absolute http, https, or mailto caption link.
      - object
        - `type` 'video', required
        - `video_url` string, required: Absolute hosted video URL. Emails render this as a linked thumbnail.
        - `thumbnail_url` string, uri, required: Hosted HTTPS image thumbnail URL.
        - `label` string, required: Video link label.
      - object
        - `type` 'columns', required
        - `ratio` '50-50' | '33-67' | '67-33'
        - `left` union, required
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `title` string, nullable, required: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `body` string, required: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `title` string, nullable: Optional column heading.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `image_url` string, uri, nullable, required: Optional hosted HTTPS image URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `cta_label` string, nullable, required: Optional call-to-action label.
            - `cta_url` string, nullable, required: Optional http, https, or mailto call-to-action URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
        - `right` union, required
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `title` string, nullable, required: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `body` string, required: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `title` string, nullable: Optional column heading.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `image_url` string, uri, nullable, required: Optional hosted HTTPS image URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `cta_label` string, nullable, required: Optional call-to-action label.
            - `cta_url` string, nullable, required: Optional http, https, or mailto call-to-action URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
      - object
        - `type` 'link_list', required
        - `title` string, nullable: Optional link list title.
        - `items` object[], required
          - `label` string, required: Link label.
          - `url` string, required: Absolute http, https, or mailto URL.
          - `description` string, nullable: Optional description shown under the link.
      - object
        - `type` 'quote', required
        - `body` string, required: Bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
        - `cite` string, nullable: Optional quote citation.
      - object
        - `type` 'divider', required
      - object
        - `type` 'spacer', required
        - `height` integer
      - object
        - `type` 'code', required
        - `code` string, required: Code text.
      - object
        - `type` 'custom_html', required
        - `html` string, required: Custom email-safe HTML fragment.
  - `content_markdown` string: The body as Markdown, instead of blocks or body_html. Shipmail converts headings, paragraphs, lists, quotes, code, images, links, dividers and tables to blocks and stores blocks only. A callout starts with a line `:::callout` (optionally followed by info, warning or success, then a title) and ends with a line `:::`. Raw HTML stays visible text. Send only one of blocks, body_html or content_markdown.
  - `subject_b` string, nullable: A second subject to test against subject. Each goes to a slice of subject_test_percent of the subscribers; after subject_test_hours the one with more human clicks goes to the rest. Opens do not decide, because Apple Mail Privacy Protection opens every message. Requires track_engagement. Null removes the test.
  - `subject_test_percent` integer, nullable
  - `subject_test_hours` integer, nullable

## Response `200`

Newsletter.

- Newsletter
  - `object` 'newsletter', required
  - `id` string, required
  - `audience_id` string, nullable, required
  - `sender_identity_id` string, nullable, required
  - `newsletter_domain_id` string, nullable, required
  - `name` string, required
  - `subject` string, nullable
  - `preview_text` string, nullable
  - `from_name` string, nullable
  - `from_address` string
  - `reply_to_address` string, nullable
  - `blocks` NewsletterBlock[], nullable: Structured blocks this draft was authored from. body_html and body_text are rendered from these blocks on every draft save. Null for newsletters sent before blocks existed.
    - union: Structured newsletter block. paragraph.body, quote.body, callout.body, list items, and column bodies accept bare text or restricted inline HTML. Shipmail sanitizes these values when it stores the blocks and renders email-safe HTML and text.
      - object
        - `type` 'heading', required
        - `text` string, required: Heading text.
        - `level` 1 | 2 | 3
      - object
        - `type` 'paragraph', required
        - `body` string, required: Bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks and HTML entities for literal tag-like text.
      - object
        - `type` 'list', required
        - `ordered` boolean
        - `items` string[], required
      - object
        - `type` 'callout', required
        - `title` string, nullable: Optional callout title.
        - `body` string, required: Bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
        - `variant` 'accent' | 'info' | 'warning' | 'success'
      - object
        - `type` 'button', required
        - `label` string, required: Button label.
        - `url` string, required: Absolute http, https, or mailto URL.
        - `align` 'left' | 'center' | 'right': Horizontal alignment of the button.
      - object
        - `type` 'image', required
        - `url` string, uri, required: Hosted HTTPS image URL.
        - `alt` string, required: Image alt text.
        - `align` 'left' | 'center' | 'right': Horizontal alignment of the image and its caption.
        - `link_url` string, nullable: Optional absolute http, https, or mailto image link.
        - `caption` string, nullable: Optional image caption.
        - `caption_url` string, nullable: Optional absolute http, https, or mailto caption link.
      - object
        - `type` 'video', required
        - `video_url` string, required: Absolute hosted video URL. Emails render this as a linked thumbnail.
        - `thumbnail_url` string, uri, required: Hosted HTTPS image thumbnail URL.
        - `label` string, required: Video link label.
      - object
        - `type` 'columns', required
        - `ratio` '50-50' | '33-67' | '67-33'
        - `left` union, required
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `title` string, nullable, required: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `body` string, required: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `title` string, nullable: Optional column heading.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `image_url` string, uri, nullable, required: Optional hosted HTTPS image URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Left column content. Include at least one heading, body, image, or CTA field.
            - `cta_label` string, nullable, required: Optional call-to-action label.
            - `cta_url` string, nullable, required: Optional http, https, or mailto call-to-action URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
        - `right` union, required
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `title` string, nullable, required: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `body` string, required: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `title` string, nullable: Optional column heading.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `image_url` string, uri, nullable, required: Optional hosted HTTPS image URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
            - `cta_label` string, nullable: Optional call-to-action label.
            - `cta_url` string, nullable: Optional http, https, or mailto call-to-action URL.
          - object: Right column content. Include at least one heading, body, image, or CTA field.
            - `cta_label` string, nullable, required: Optional call-to-action label.
            - `cta_url` string, nullable, required: Optional http, https, or mailto call-to-action URL.
            - `title` string, nullable: Optional column heading.
            - `body` string: Optional bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
            - `image_url` string, uri, nullable: Optional hosted HTTPS image URL.
            - `image_alt` string, nullable: Alt text for image_url.
            - `image_fit` 'natural' | 'contain' | 'cover': Optional image sizing. Natural preserves the source ratio; contain shows the whole image in a 4:3 frame; cover crops to fill a 4:3 frame.
      - object
        - `type` 'link_list', required
        - `title` string, nullable: Optional link list title.
        - `items` object[], required
          - `label` string, required: Link label.
          - `url` string, required: Absolute http, https, or mailto URL.
          - `description` string, nullable: Optional description shown under the link.
      - object
        - `type` 'quote', required
        - `body` string, required: Bare text or sanitized inline HTML. Allowed tags: a, b, br, code, em, i, p, s, span, strong, and u. Use p or br for line breaks.
        - `cite` string, nullable: Optional quote citation.
      - object
        - `type` 'divider', required
      - object
        - `type` 'spacer', required
        - `height` integer
      - object
        - `type` 'code', required
        - `code` string, required: Code text.
      - object
        - `type` 'custom_html', required
        - `html` string, required: Custom email-safe HTML fragment.
  - `body_html` string, nullable: Rendered email HTML, derived from blocks for drafts. Read-only.
  - `body_text` string, nullable: Plain-text body, derived from blocks unless a manual override was set. Read-only.
  - `status` 'draft' | 'imported' | 'pending_approval' | 'approved' | 'scheduled' | 'sending' | 'paused' | 'sent' | 'cancelled' | 'failed', required
  - `archive_visibility` 'private' | 'public', required
  - `feed_entry_url` string, uri, nullable, required: Optional http(s) Atom entry destination. Feed readers link the newsletter title here instead of to its Shipmail web archive, including when the archive is private.
  - `styling_mode` 'styled' | 'plain', required: styled applies Shipmail's email theme. plain sends your HTML without injected styles, width, or centering, so the reader's email client styles it.
  - `track_engagement` boolean, required: Whether this newsletter tracks opens and clicks.
  - `add_utm_tags` boolean, required: Whether this newsletter adds UTM tags to its links. Adds utm_source=shipmail, utm_medium (email or feed) and utm_campaign (a slug of the subject) to the newsletter's http and https links. Links that already carry a utm_ parameter, links with a merge tag in the host, and Shipmail's own unsubscribe and archive links are left alone. The web archive is never tagged.
  - `opened_count` integer, nullable, required: Unique recipients with at least one counted open. Opens that Apple Mail Privacy Protection preloads are not counted. Null when track_engagement is false.
  - `clicked_count` integer, nullable, required: Unique recipients who clicked at least one tracked link, excluding clicks attributed to link scanners. Null when track_engagement is false.
  - `send_limit` integer, nullable, required: The limit the newsletter was scheduled with: only this many of the most engaged subscribers went first. Null sends to everyone.
  - `held_count` integer, required: Subscribers held past send_limit. Send them the newsletter with POST /newsletters/{id}/send-more.
  - `subject_b` string, nullable, required: A second subject tested against subject. Requires track_engagement.
  - `subject_test_percent` integer, nullable: The share of subscribers each subject goes to first, from 1 to 25. Null when there is no subject test.
  - `subject_test_hours` integer, nullable: Hours after both test slices finish before the subject with more human clicks goes to the rest, from 1 to 72.
  - `subject_test_winner` 'a' | 'b' | 'null', nullable, required: a is subject, b is subject_b. Null until the test decides. A tie keeps a.
  - `subject_test_decided_at` string, date-time, nullable
  - `preflight_status` 'not_run' | 'passed' | 'warning' | 'failed', required
  - `preflight_results` object
  - `send_window_hours` integer
  - `send_rate_per_hour` integer
  - `recipient_count` integer
  - `sent_count` integer
  - `delivered_count` integer
  - `bounced_count` integer
  - `complained_count` integer
  - `failed_count` integer
  - `skipped_count` integer
  - `scheduled_at` string, date-time, nullable
  - `approved_at` string, date-time, nullable
  - `started_at` string, date-time, nullable
  - `published_at` string, date-time, nullable, required: Stable first-publication timestamp.
  - `archive_url` string, uri, nullable, required: Canonical Shipmail public archive URL.
  - `completed_at` string, date-time, nullable
  - `cancelled_at` string, date-time, nullable
  - `created_at` string, date-time, required
  - `updated_at` string, date-time, required
  - `last_test_sent_at` string, date-time, nullable
  - `last_test_recipient` string, nullable
  - `content_changed_since_test_send` boolean

## Other responses

- `404`: Resource not found.
- `409`: Resource conflict.
- `422`: Validation failed.
- `429`: Rate limit exceeded.

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[API](https://skmtc.dev/shipmail/apis/shipmail-api.md) · [All operations](https://skmtc.dev/shipmail/apis/shipmail-api/llms.txt) · [OpenAPI document](https://skmtc.dev/shipmail/apis/shipmail-api/revisions/2c23e59d7e30?raw)