> ## Documentation Index > Fetch the complete documentation index at: https://docs.unifygtm.com/llms.txt > Use this file to discover all available pages before exploring further. # Update enrollment step > Edit one person's email copy before it sends. ## Overview Replace the subject, fallback subject, or body of one person's email before it sends. The change applies only to this enrollment and leaves the sequence's template unchanged. Use it to revise copy that Unify drafted for an [agentic sequence](/reference/sequences/personalization/agentic-sequences) before you [approve the enrollment](/developers/api/sequences/enrollments/approve), or to adjust a scheduled email for one recipient. Include only the fields you want to change. The request must include at least one of `subject`, `fallback_subject`, or `body`. Only email steps have copy; other step types return `400 Bad Request`. Get step IDs from [List enrollment steps](/developers/api/sequences/enrollments/list-steps). ## Examples Set `UNIFY_API_KEY` to your API key and replace the example step ID and `version_id` with values from [Get enrollment step](/developers/api/sequences/enrollments/get-step). This request replaces the email body and keeps the first-name variable from the original copy: ```bash theme={null} curl --request PATCH \ --url "https://api.unifygtm.com/sequences/v1/enrollment-steps/3f6c2a90-58d1-4e7b-9a43-2c8e1d7b5f06" \ --header "X-Api-Key: $UNIFY_API_KEY" \ --header "Content-Type: application/json" \ --data '{ "body": "

Hi {{variable::person.firstName}},

Congratulations on the new office in Austin. Would a short call next week be useful?

", "version_id": "0b7d9e4c-6a21-4f3e-8c55-9d1a2b3c4e5f" }' ``` The response returns the step with its new copy and a new `email.version_id`. Send a subject only to the first email of a thread: ```json theme={null} { "subject": "{{variable::company.name}} and Unify", "fallback_subject": "Quick introduction", "version_id": "0b7d9e4c-6a21-4f3e-8c55-9d1a2b3c4e5f" } ``` Unify uses `fallback_subject` if the variable in `subject` cannot be resolved when the email sends. ## Write the copy `body` is HTML and replaces the step's entire body. Template variables and [snippets](/reference/sequences/personalization/snippets) appear in the copy as `{{ ... }}` tokens, such as `{{variable::person.firstName}}`. Keep the tokens you want to preserve. To add a variable or snippet, copy its token from the sequence's template, which [Get sequence step](/developers/api/sequences/sequences/get-step) returns in `config.body`. After an update, Unify resolves the tokens in the new copy for this person. `email.is_ready` is `false` until they are resolved, and the email does not send before then. Only the first email of a thread accepts `subject` and `fallback_subject`. Its `email.is_root_message` is `true`. Later emails reply in the same thread and reuse its subject, so a subject change on a reply returns `400 Bad Request`. ## Avoid overwriting other edits Send the `email.version_id` you last read as `version_id`. If the copy changed after that version, for example because a teammate edited it in Unify, the API returns `409 Conflict` with `reason` set to `VERSION_OUTDATED`. Get the step again, apply your change to the latest copy, and retry. Without `version_id`, the update replaces the current copy regardless of earlier changes. The API also returns `409 Conflict` once the step has sent or the enrollment has ended, for example because the person replied or opted out. `reason` identifies the cause. Only `VERSION_OUTDATED` can be resolved by retrying. ## OpenAPI ````yaml PATCH /sequences/v1/enrollment-steps/{id} openapi: 3.1.0 info: title: Unify Sequences API summary: Interact with sequences and sequence enrollments within the Unify platform. version: '1' termsOfService: https://www.unifygtm.com/legal/terms-and-conditions contact: name: Unify Support url: https://www.unifygtm.com/support email: support@unifygtm.com servers: - url: https://api.unifygtm.com variables: {} security: - ApiKeyAuth: [] tags: - name: Sequences - name: Sequence Enrollment Steps - name: Sequence Enrollments paths: /sequences/v1/enrollment-steps/{id}: patch: tags: - Sequences - Sequence Enrollment Steps description: |- Update the email copy of an enrollment step that has not been sent yet. Returns a bad request for steps that are not email steps and for subject changes on reply messages. Returns a conflict once the step has finished or the enrollment has ended. operationId: update_sequence_enrollment_step parameters: - name: id in: path required: true schema: $ref: '#/components/schemas/uuid' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/UpdateEnrollmentStepRequest' responses: '200': description: Response returned when an enrollment step's email copy is updated. content: application/json: schema: $ref: '#/components/schemas/UpdateEnrollmentStepSuccessResponse' '400': description: Response for any operation that results in a bad request error. content: application/json: schema: type: object required: - status properties: status: type: string enum: - bad_request errors: type: array items: $ref: '#/components/schemas/UResponses.BadRequestError' message: type: string description: >- Response for any operation that results in a bad request error. '401': description: Response for any operation that results in an unauthorized error. content: application/json: schema: type: object required: - status - message properties: status: type: string enum: - unauthorized message: type: string description: >- Response for any operation that results in an unauthorized error. '404': description: Response returned when an enrollment step cannot be found. content: application/json: schema: $ref: '#/components/schemas/EnrollmentStepNotFoundResponse' '409': description: >- Response returned when an enrollment step's email copy can no longer be updated. content: application/json: schema: $ref: '#/components/schemas/EnrollmentStepUpdateConflictResponse' '429': description: Response for any operation that exceeds a rate limit. content: application/json: schema: type: object required: - status - message properties: status: type: string enum: - rate_limited message: type: string description: Response for any operation that exceeds a rate limit. '500': description: Response for any operation that results in an internal server error. content: application/json: schema: type: object required: - status - message properties: status: type: string enum: - error message: type: string description: >- Response for any operation that results in an internal server error. components: schemas: uuid: type: string format: uuid description: String UUID value. UpdateEnrollmentStepRequest: anyOf: - type: object properties: subject: type: string fallback_subject: type: string body: type: string minLength: 1 maxLength: 200000 version_id: $ref: '#/components/schemas/uuid' required: - subject - type: object properties: subject: type: string fallback_subject: type: string body: type: string minLength: 1 maxLength: 200000 version_id: $ref: '#/components/schemas/uuid' required: - fallback_subject - type: object properties: subject: type: string fallback_subject: type: string body: type: string minLength: 1 maxLength: 200000 version_id: $ref: '#/components/schemas/uuid' required: - body description: >- Request body for updating the email copy of an enrollment step. At least one of `subject`, `fallback_subject` or `body` must be provided. - `subject` and `fallback_subject` are only accepted on root messages. - `body` is HTML. Template variables and snippets are written as `{{ ... }}` tokens. Must not be blank. - `version_id` is the copy version the edit is based on. The update is rejected with a conflict when the copy has changed since that version. UpdateEnrollmentStepSuccessResponse: type: object allOf: - $ref: '#/components/schemas/EnrollmentStep' description: Response returned when an enrollment step's email copy is updated. UResponses.BadRequestError: type: object required: - code properties: code: type: string path: type: array items: anyOf: - type: string - type: integer object_api_name: type: string attribute_api_name: type: string allOf: - type: object unevaluatedProperties: {} description: Validation error detail returned for bad request responses. EnrollmentStepNotFoundResponse: type: object allOf: - type: object required: - status - message properties: status: type: string enum: - not_found message: type: string description: Response for any operation that results in a not found error. description: Response returned when an enrollment step cannot be found. EnrollmentStepUpdateConflictResponse: type: object required: - reason properties: reason: $ref: '#/components/schemas/EnrollmentStepUpdateConflictReason' allOf: - type: object required: - status - message properties: status: type: string enum: - state_conflict message: type: string description: Response for any operation that results in a conflict error. description: |- Response returned when an enrollment step's email copy can no longer be updated. EnrollmentStep: type: object required: - id - created_at - updated_at - enrollment_id - sequence_id - step_id - type - status - step_number - is_blocked - is_bounced - is_canceled - is_opted_out - is_paused - is_replied - started_at - ended_at - email properties: id: $ref: '#/components/schemas/uuid' created_at: $ref: '#/components/schemas/datetime' updated_at: $ref: '#/components/schemas/datetime' enrollment_id: $ref: '#/components/schemas/uuid' sequence_id: $ref: '#/components/schemas/uuid' step_id: $ref: '#/components/schemas/uuid' description: ID of the sequence step this enrollment step was created from. type: $ref: '#/components/schemas/SequenceEnrollmentStepType' status: $ref: '#/components/schemas/SequenceEnrollmentStepStatus' step_number: anyOf: - type: integer - type: 'null' minimum: 1 description: >- Position of the step in the enrollment, starting at 1. Null until the step is expected to run or has finished. is_blocked: type: boolean is_bounced: type: boolean is_canceled: type: boolean is_opted_out: type: boolean is_paused: type: boolean is_replied: type: boolean started_at: anyOf: - $ref: '#/components/schemas/datetime' - type: 'null' ended_at: anyOf: - $ref: '#/components/schemas/datetime' - type: 'null' email: anyOf: - $ref: '#/components/schemas/EnrollmentStepEmail' - type: 'null' description: Email copy for email steps. Null for other step types. description: One step of a person's enrollment in a sequence. EnrollmentStepUpdateConflictReason: type: string enum: - STEP_COMPLETED - PERSON_REPLIED - PERSON_OPTED_OUT - PERSON_EXCLUDED - ENROLLMENT_CANCELED - ENROLLMENT_ENDED - VERSION_OUTDATED description: Reason an enrollment step's email copy can no longer be updated. datetime: type: string format: date-time description: String value representing an RFC 3339 datetime. SequenceEnrollmentStepType: type: string enum: - AUTOMATIC_EMAIL - MANUAL_EMAIL - ACTION_ITEM - ZAPIER - PHONE_CALL - MANUAL_LINKEDIN_PROFILE_VIEW - MANUAL_LINKEDIN_CONNECTION - MANUAL_LINKEDIN_MESSAGE description: Type of a sequence enrollment step. SequenceEnrollmentStepStatus: type: string enum: - NOT_STARTED - SCHEDULED - PENDING - FINISHED - CANCELED - ERRORED - UNREACHABLE description: Status of an individual sequence enrollment step. EnrollmentStepEmail: type: object required: - version_id - subject - fallback_subject - body - is_ready - is_edited - is_root_message - is_blocked - scheduled_send_at - sent_at properties: version_id: $ref: '#/components/schemas/uuid' description: >- ID of the current version of the copy. Changes every time the copy is updated. subject: anyOf: - type: string - type: 'null' fallback_subject: anyOf: - type: string - type: 'null' description: |- Subject used at send time when `subject` still contains unresolved template variables. body: anyOf: - type: string - type: 'null' description: >- HTML body of the email. Template variables and snippets are kept as `{{ ... }}` tokens and are resolved at send time. Null while the copy is being prepared. is_ready: type: boolean description: >- False while template variables and snippets are still being resolved. The email is not sent until the copy is ready. is_edited: type: boolean description: True when the copy was changed after it was first generated. is_root_message: type: boolean description: >- True for the first email of a thread. Subjects can only be set on root messages. Replies reuse the thread's subject. is_blocked: type: boolean description: |- True when the email cannot be sent in its current state, for example because of unresolved template variables or a mailbox problem. scheduled_send_at: anyOf: - $ref: '#/components/schemas/datetime' - type: 'null' sent_at: anyOf: - $ref: '#/components/schemas/datetime' - type: 'null' description: Email copy prepared for one enrollment step. securitySchemes: ApiKeyAuth: type: apiKey in: header name: x-api-key ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.