With this endpoint you can update (fully replace) email content by ID.
The full content structure must be provided in the request body.
If the stored content is text-only (variant: text), it must keep exactly one text block with no role and no section may reference a universal layout; any other structure is rejected with 400 on sections.

Scopes:
email-templates.write

Rate Limiting:
This endpoint is rate limited to 400 requests per minute.