> ## Documentation Index > Fetch the complete documentation index at: https://docs.maildiver.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Update automation contact properties > **Endpoint:** `v1/automation/contacts/{email}` Update a contact's properties using deep merge with null deletion. Properties can be used in workflow conditions and email personalization. **Merge Behavior:** - **Omitted fields**: Preserved unchanged in existing properties - **Fields with values**: Updated or added to properties - **Fields set to `null`**: Explicitly deleted from properties - **Nested objects**: Recursively merged (NOT replaced entirely) - **Arrays**: Replaced entirely (NOT merged element-wise) **Unsubscribe Management:** To manage subscriptions, include `{{ unsubscribe_url }}` in your email templates. When a contact clicks this link, they will be automatically unsubscribed from the workflow. Subscription status cannot be managed via this endpoint. **Note:** Contact must exist before updating. Send an event first to create the contact. ## OpenAPI ````yaml api-reference/openapi.yml patch /automation/contacts/{email} openapi: 3.1.0 info: title: Send Email API description: > Send transactional emails through MailDiver. ### Base URL All API endpoints are prefixed with `api.` subdomain: ``` https://api.maildiver.com ``` For the self-hosted version, if your domain is `example.com`: ``` https://api.example.com ``` ### Endpoint ``` v1/emails ``` ### Authentication All API requests require authentication using your API key in the Authorization header: ``` Authorization: Bearer your-api-key ``` version: 1.0.0 license: name: MIT servers: - url: https://api.maildiver.com/v1 description: Production server variables: domain: default: yourdomain.com description: Your domain (without the api. prefix) security: - bearerAuth: [] paths: /automation/contacts/{email}: patch: tags: - Automation Contact summary: Update automation contact properties description: > **Endpoint:** `v1/automation/contacts/{email}` Update a contact's properties using deep merge with null deletion. Properties can be used in workflow conditions and email personalization. **Merge Behavior:** - **Omitted fields**: Preserved unchanged in existing properties - **Fields with values**: Updated or added to properties - **Fields set to `null`**: Explicitly deleted from properties - **Nested objects**: Recursively merged (NOT replaced entirely) - **Arrays**: Replaced entirely (NOT merged element-wise) **Unsubscribe Management:** To manage subscriptions, include `{{ unsubscribe_url }}` in your email templates. When a contact clicks this link, they will be automatically unsubscribed from the workflow. Subscription status cannot be managed via this endpoint. **Note:** Contact must exist before updating. Send an event first to create the contact. operationId: updateAutomationContact parameters: - name: email in: path required: true description: Contact's email address schema: type: string example: user@example.com requestBody: required: true content: application/json: schema: type: object properties: properties: type: object description: >- Contact properties to merge (key-value pairs, set to null to delete) example: first_name: John plan: enterprise examples: basic_update: summary: Basic update value: properties: first_name: John last_name: Doe plan: enterprise delete_field: summary: Delete field with null value: properties: old_field: null merge_nested: summary: Merge nested object (preserves unchanged nested fields) value: properties: user: profile: avatar: new-photo.jpg delete_nested_field: summary: Delete nested field value: properties: user: profile: avatar: null replace_array: summary: Replace array entirely value: properties: tags: - new - tags delete_array: summary: Delete array with null value: properties: tags: null responses: '200': description: Contact successfully updated content: application/json: examples: success: summary: Success response value: message: Contact metadata updated successfully email: user@example.com updated_properties: - first_name - last_name - plan - company '400': description: Bad request content: application/json: examples: emailRequired: summary: Email is required value: error: Email is required invalidEmail: summary: Invalid email format value: error: Invalid email format invalidJson: summary: Invalid JSON payload value: error: Invalid JSON payload invalidProperties: summary: Invalid properties value: error: properties must be an object emptyProperties: summary: Empty properties value: error: properties cannot be empty '403': description: Forbidden (API key is missing or invalid) content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: Contact not found content: application/json: examples: notFound: summary: Contact not found value: error: >- Contact not found. Send an event first to create the contact. '500': description: Internal server error content: application/json: examples: serverError: summary: Internal server error value: error: Failed to update contact metadata details: Unknown error components: schemas: Error: type: object properties: message: type: string description: Error description description: | Error response with message. ### Common Errors #### 400 Bad Request Validation errors return only the error message: ```json { "message": "from field is required" } ``` Common validation messages: - `"from field is required"` - `"to field is required"` - `"subject field is required"` - `"html content size (42MB) exceeds maximum of 40MB"` - `"Too many recipients: 51. Maximum allowed is 50"` - `"Invalid email format in from field"` - `"template_id cannot be used together with html"` #### 403 Forbidden Authentication errors include both message and code: ```json { "message": "Invalid API key", "code": "invalid_api_key" } ``` ```json { "message": "Invalid authorization header", "code": "invalid_authorization_header" } ``` #### 404 Not Found ```json { "message": "Template 'welcome-email' not found" } ``` securitySchemes: bearerAuth: type: http scheme: bearer description: API key with format "Bearer {your-api-key}" ````