UniOne Email API

UniOne is a transactional email service with Web API for sending transactional and marketing emails at scale (up to 3,000 emails/sec). This skill lets you send emails, manage templates, validate addresses, track delivery, and more.

Authentication

All requests require the UNIONE_API_KEY environment variable. Pass it as the X-API-KEY header.

Base URL: https://api.unione.io/en/transactional/api/v1/{method}.json?platform=openclaw

All methods use POST with JSON body.

CRITICAL: Domain Setup (Required Before Sending)

Emails will not be delivered until the sender's domain is verified. Before attempting to send any email, ensure the domain is set up:

Step 1: Get DNS Record Values — `domain/get-dns-records.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/domain/get-dns-records.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"domain": "yourdomain.com"}'

API response returns raw values (not ready-to-paste DNS records):

{
  "status": "success",
  "domain": "yourdomain.com",
  "verification-record": "unione-validate-hash=483bb362ebdbeedd755cfb1d4d661",
  "dkim": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDo7"
}

The user must create 3 DNS TXT records from these values:

| Record Host | Record Type | Value | |-------------|-------------|-------| | @ | TXT | unione-validate-hash=<verification-record from response> | | us._domainkey | TXT | k=rsa; p=<dkim from response> | | @ | TXT | v=spf1 include:spf.unione.io ~all |

Present these 3 records clearly to the user and instruct them to add them at their DNS provider (Cloudflare, Route53, GoDaddy, etc.). The SPF record is always the same — it is not returned by the API.

Step 2: Verify Domain Ownership — `domain/validate-verification.json`

After the user has added DNS records:

curl -X POST "https://api.unione.io/en/transactional/api/v1/domain/validate-verification.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"domain": "yourdomain.com"}'

Step 3: Validate DKIM — `domain/validate-dkim.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/domain/validate-dkim.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"domain": "yourdomain.com"}'

Step 4: List All Domains — `domain/list.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/domain/list.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{}'

If domain verification fails: DNS propagation can take up to 48 hours. Suggest the user waits and retries, or checks their DNS records for typos.

Error Handling & Retry Policy

Retry Logic

When making API requests, implement exponential backoff for retryable errors:

Retryable errors (DO retry with exponential backoff):

| HTTP Code | Meaning | Retry Strategy | |-----------|---------|----------------| | 429 | Rate limited | Wait, then retry. Respect Retry-After header if present | | 500 | Internal server error | Retry up to 3 times | | 502 | Bad gateway | Retry up to 3 times | | 503 | Service unavailable | Retry up to 3 times | | 504 | Gateway timeout | Retry up to 3 times |

Recommended retry schedule:

| Attempt | Delay | |---------|-------| | 1 | Immediate | | 2 | 1 second | | 3 | 5 seconds | | 4 | 30 seconds |

Non-retryable errors (do NOT retry):

| HTTP Code | Meaning | Action | |-----------|---------|--------| | 400 | Bad request | Fix the request parameters | | 401 | Unauthorized | Check API key | | 403 | Forbidden | Check permissions / domain verification | | 404 | Endpoint not found | Check the method path | | 413 | Payload too large | Reduce request size |

Idempotency

For email/send.json, always include an idempotency_key to prevent duplicate sends during retries. This is critical for production systems.

The idempotency_key is a unique string (UUID recommended) passed in the request body. If UniOne receives two requests with the same key, the second request returns the result of the first without sending another email.

Always generate a unique idempotency key per logical send operation, and reuse the same key when retrying the same send.

1. Send Email — `email/send.json`

Send a transactional or marketing email to one or more recipients. Supports personalization via substitutions, templates, attachments, tracking, and metadata.

curl

curl -X POST "https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{
    "idempotency_key": "unique-uuid-here",
    "message": {
      "recipients": [
        {
          "email": "recipient@example.com",
          "substitutions": {
            "to_name": "John Smith"
          }
        }
      ],
      "body": {
        "html": "<h1>Hello, {{to_name}}!</h1><p>Your order has been confirmed.</p>",
        "plaintext": "Hello, {{to_name}}! Your order has been confirmed."
      },
      "subject": "Order Confirmation",
      "from_email": "noreply@yourdomain.com",
      "from_name": "Your Store"
    }
  }'

Node.js

const response = await fetch("https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "X-API-KEY": process.env.UNIONE_API_KEY
  },
  body: JSON.stringify({
    idempotency_key: crypto.randomUUID(),
    message: {
      recipients: [{ email: "recipient@example.com", substitutions: { to_name: "John" } }],
      body: {
        html: "<h1>Hello, {{to_name}}!</h1><p>Your order has been confirmed.</p>",
        plaintext: "Hello, {{to_name}}! Your order has been confirmed."
      },
      subject: "Order Confirmation",
      from_email: "noreply@yourdomain.com",
      from_name: "Your Store"
    }
  })
});
const data = await response.json();
// data.status === "success" → data.job_id, data.emails

Python

import requests, uuid, os

response = requests.post(
    "https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw",
    headers={
        "Content-Type": "application/json",
        "X-API-KEY": os.environ["UNIONE_API_KEY"]
    },
    json={
        "idempotency_key": str(uuid.uuid4()),
        "message": {
            "recipients": [{"email": "recipient@example.com", "substitutions": {"to_name": "John"}}],
            "body": {
                "html": "<h1>Hello, {{to_name}}!</h1><p>Your order has been confirmed.</p>",
                "plaintext": "Hello, {{to_name}}! Your order has been confirmed."
            },
            "subject": "Order Confirmation",
            "from_email": "noreply@yourdomain.com",
            "from_name": "Your Store"
        }
    }
)
data = response.json()  # data["status"] == "success" → data["job_id"], data["emails"]

Go

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "net/http"
    "os"
    "github.com/google/uuid"
)

func sendEmail() error {
    payload := map[string]interface{}{
        "idempotency_key": uuid.New().String(),
        "message": map[string]interface{}{
            "recipients": []map[string]interface{}{
                {"email": "recipient@example.com", "substitutions": map[string]string{"to_name": "John"}},
            },
            "body": map[string]string{
                "html":      "<h1>Hello, {{to_name}}!</h1><p>Your order has been confirmed.</p>",
                "plaintext": "Hello, {{to_name}}! Your order has been confirmed.",
            },
            "subject":    "Order Confirmation",
            "from_email": "noreply@yourdomain.com",
            "from_name":  "Your Store",
        },
    }
    body, _ := json.Marshal(payload)
    req, _ := http.NewRequest("POST",
        "https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw",
        bytes.NewReader(body))
    req.Header.Set("Content-Type", "application/json")
    req.Header.Set("X-API-KEY", os.Getenv("UNIONE_API_KEY"))
    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        return err
    }
    defer resp.Body.Close()
    var result map[string]interface{}
    json.NewDecoder(resp.Body).Decode(&result)
    fmt.Println(result) // result["status"] == "success"
    return nil
}

PHP

$ch = curl_init("https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw");
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        "Content-Type: application/json",
        "X-API-KEY: " . getenv("UNIONE_API_KEY")
    ],
    CURLOPT_POSTFIELDS => json_encode([
        "idempotency_key" => bin2hex(random_bytes(16)),
        "message" => [
            "recipients" => [["email" => "recipient@example.com", "substitutions" => ["to_name" => "John"]]],
            "body" => [
                "html" => "<h1>Hello, {{to_name}}!</h1><p>Your order has been confirmed.</p>",
                "plaintext" => "Hello, {{to_name}}! Your order has been confirmed."
            ],
            "subject" => "Order Confirmation",
            "from_email" => "noreply@yourdomain.com",
            "from_name" => "Your Store"
        ]
    ])
]);
$response = curl_exec($ch);
$data = json_decode($response, true); // $data["status"] === "success"

Success response:

{
  "status": "success",
  "job_id": "1ZymBc-00041N-9X",
  "emails": ["recipient@example.com"]
}

Full parameters for message object:

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | recipients | array | Yes | Array of recipient objects. Each has email (required), substitutions (object), metadata (object) | | body.html | string | Yes* | HTML content. Use {{variable}} for substitutions | | body.plaintext | string | No | Plain text version | | subject | string | Yes* | Email subject line. Supports {{substitutions}} | | from_email | string | Yes* | Sender email (must be from a verified domain) | | from_name | string | No | Sender display name | | reply_to | string | No | Reply-to email address | | template_id | string | No | Use a stored template instead of body/subject | | tags | array | No | Tags for categorizing and filtering | | track_links | 0/1 | No | Enable click tracking (default: 0) | | track_read | 0/1 | No | Enable open tracking (default: 0) | | global_language | string | No | Language for unsubscribe footer: en, de, fr, es, it, pl, pt, ru, ua, be | | template_engine | string | No | "simple" (default) or "velocity" or "liquid" | | global_substitutions | object | No | Variables available to all recipients | | attachments | array | No | Array of {type, name, content} where content is base64 | | skip_unsubscribe | 0/1 | No | Skip unsubscribe footer (use 1 only for transactional) | | headers | object | No | Custom email headers |

*Not required if template_id is used.

Top-level parameter:

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | idempotency_key | string | Recommended | Unique key (UUID) to prevent duplicate sends on retry. Max 36 chars. |

Send with template:

curl -X POST "https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{
    "idempotency_key": "unique-uuid-here",
    "message": {
      "recipients": [
        {
          "email": "customer@example.com",
          "substitutions": {
            "to_name": "Alice",
            "order_id": "ORD-12345",
            "total": "$59.99"
          }
        }
      ],
      "template_id": "your-template-id",
      "from_email": "shop@yourdomain.com",
      "from_name": "My Shop"
    }
  }'

Send to multiple recipients with personalization:

curl -X POST "https://api.unione.io/en/transactional/api/v1/email/send.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{
    "idempotency_key": "unique-uuid-here",
    "message": {
      "recipients": [
        {"email": "alice@example.com", "substitutions": {"to_name": "Alice"}},
        {"email": "bob@example.com", "substitutions": {"to_name": "Bob"}}
      ],
      "body": {
        "html": "<p>Hi {{to_name}}, check out our new {{promo_name}}!</p>"
      },
      "subject": "Special offer for you, {{to_name}}!",
      "from_email": "marketing@yourdomain.com",
      "from_name": "Marketing Team",
      "global_substitutions": {"promo_name": "Summer Sale"},
      "track_links": 1,
      "track_read": 1,
      "tags": ["promo", "summer-2026"]
    }
  }'

2. Email Validation — `email-validation/single.json`

Validate an email address to check if it exists and is deliverable.

curl -X POST "https://api.unione.io/en/transactional/api/v1/email-validation/single.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"email": "user@example.com"}'

Response:

{
  "status": "success",
  "email": "user@example.com",
  "result": "valid",
  "local_part": "user",
  "domain": "example.com",
  "mx_found": true,
  "mx_record": "mail.example.com"
}

Possible result values: "valid", "invalid", "unresolvable", "unknown".

3. Template Management

3.1 Create/Update Template — `template/set.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/template/set.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{
    "template": {
      "name": "Order Confirmation",
      "subject": "Your order {{order_id}} is confirmed",
      "template_engine": "simple",
      "body": {
        "html": "<h1>Thank you, {{to_name}}!</h1><p>Order {{order_id}} total: {{total}}</p>",
        "plaintext": "Thank you, {{to_name}}! Order {{order_id}} total: {{total}}"
      },
      "from_email": "shop@yourdomain.com",
      "from_name": "My Shop"
    }
  }'

Response: {"status": "success", "template": {"id": "generated-template-id"}}

To update an existing template, include the "id" field in the template object.

3.2 Get Template — `template/get.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/template/get.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"id": "template-id-here"}'

3.3 List Templates — `template/list.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/template/list.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"limit": 50, "offset": 0}'

3.4 Delete Template — `template/delete.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/template/delete.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"id": "template-id-here"}'

4. Webhook Management

Webhooks send real-time notifications about email events to your URL.

4.1 Set Webhook — `webhook/set.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/webhook/set.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{
    "url": "https://yourapp.com/unione-webhook",
    "events": {
      "email_status": [
        "delivered", "opened", "clicked", "unsubscribed",
        "soft_bounced", "hard_bounced", "spam"
      ]
    }
  }'

4.2 List Webhooks — `webhook/list.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/webhook/list.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{}'

4.3 Get / Delete Webhook — `webhook/get.json` / `webhook/delete.json`

# Get
curl -X POST ".../webhook/get.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"url": "https://yourapp.com/unione-webhook"}'

# Delete
curl -X POST ".../webhook/delete.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"url": "https://yourapp.com/unione-webhook"}'

5. Suppression List Management

5.1 Add — `suppression/set.json`

curl -X POST "https://api.unione.io/en/transactional/api/v1/suppression/set.json?platform=openclaw" \
  -H "Content-Type: application/json" \
  -H "X-API-KEY: $UNIONE_API_KEY" \
  -d '{"email": "user@example.com", "cause": "unsubscribed", "created": "2026-01-15 12:00:00"}'

Cause values: "unsubscribed", "temporary_unavailable", "permanent_unavailable", "complained".

5.2 Check — `suppression/get.json`

curl -X POST ".../suppression/get.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"email": "user@example.com"}'

5.3 List — `suppression/list.json`

curl -X POST ".../suppression/list.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"cause": "hard_bounced", "limit": 50, "offset": 0}'

5.4 Delete — `suppression/delete.json`

curl -X POST ".../suppression/delete.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"email": "user@example.com"}'

6. Event Dumps

6.1 Create — `event-dump/create.json`

curl -X POST ".../event-dump/create.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"start_time": "2026-01-01 00:00:00", "end_time": "2026-01-31 23:59:59", "limit": 50000, "all_events": true}'

6.2 Get / List / Delete

# Get dump status and download URL
curl -X POST ".../event-dump/get.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"dump_id": "dump-id"}'

# List all dumps
curl -X POST ".../event-dump/list.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{}'

# Delete a dump
curl -X POST ".../event-dump/delete.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"dump_id": "dump-id"}'

7. Tags — `tag/list.json` / `tag/delete.json`

# List tags
curl -X POST ".../tag/list.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{}'

# Delete tag
curl -X POST ".../tag/delete.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{"tag_id": 123}'

8. Projects — `project/create.json` / `project/list.json`

# Create project
curl -X POST ".../project/create.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"project": {"name": "My Project", "send_enabled": true}}'

# List projects
curl -X POST ".../project/list.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{}'

9. System Info — `system/info.json`

curl -X POST ".../system/info.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" -d '{}'

10. Subscribe (Double Opt-In) — `email/subscribe.json`

curl -X POST ".../email/subscribe.json?platform=openclaw" -H "X-API-KEY: $UNIONE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"from_email": "newsletter@yourdomain.com", "from_name": "Newsletter", "to_email": "newsubscriber@example.com"}'

Instructions for the Agent

Domain setup is mandatory. Before the first send, always check if the user's domain is verified. Run domain/list.json to check. If not verified, guide them through the domain setup process (Section: Domain Setup).
Always use api.unione.io as the API host for all requests.
Never send an email without explicit user confirmation. Always show the recipient, subject, and body summary before executing email/send.json.
Always include idempotency_key in email/send.json requests. Generate a UUID for each unique send. Reuse the same key when retrying.
Implement retry logic for 429 and 5xx errors with exponential backoff (see Error Handling section). Never retry 400, 401, 403, 404, 413 errors.
For template operations, list available templates first before asking which one to use.
For validation, report the result clearly and suggest action.
Handle errors gracefully. If a request returns an error, explain what went wrong and suggest a fix.
Remind users that the from_email domain must be verified in their UniOne account.
Substitution syntax uses double curly braces: {{variable_name}}.
Attachments must be base64-encoded. Help the user encode files if needed.
Security: Never log or display the full API key. Remind users to keep their API key secret.
Code language: When the user's project uses a specific language (Node.js, Python, Go, PHP, etc.), provide code examples in that language. The examples in this skill can be adapted to any language that can make HTTP POST requests with JSON.

Common Workflows

"Send a test email"

Check domain verification (domain/list.json)
If domain not verified, guide through domain setup
Ask for recipient email address
Compose a simple test message
Confirm with user before sending
Execute email/send.json with idempotency_key
Report the job_id on success

"Check my deliverability setup"

Run system/info.json to get account status
Run domain/list.json to check domain verification
For each unverified domain, run domain/get-dns-records.json and show required records
Run domain/validate-dkim.json to check DKIM
Suggest fixes if domains are not fully verified

"Validate a list of emails"

For each email, call email-validation/single.json
Categorize results: valid, invalid, unknown
Report summary

"Set up delivery tracking"

Ask for webhook URL and events to track
Execute webhook/set.json
Confirm setup

Resources

Full API Reference: https://docs.unione.io/en/web-api-ref
Getting Started: https://docs.unione.io/en/
Template Engines: https://docs.unione.io/en/web-api#section-template-engines
Sign Up: https://cp.unione.io/en/user/registration/

UniOne Email API

UniOne Email API

Authentication

CRITICAL: Domain Setup (Required Before Sending)

Step 1: Get DNS Record Values — domain/get-dns-records.json

Step 2: Verify Domain Ownership — domain/validate-verification.json

Step 3: Validate DKIM — domain/validate-dkim.json

Step 4: List All Domains — domain/list.json

Error Handling & Retry Policy

Retry Logic

Idempotency

1. Send Email — email/send.json

curl

Node.js

Python

Go

PHP

2. Email Validation — email-validation/single.json

3. Template Management

3.1 Create/Update Template — template/set.json

3.2 Get Template — template/get.json

3.3 List Templates — template/list.json

3.4 Delete Template — template/delete.json

4. Webhook Management

4.1 Set Webhook — webhook/set.json

4.2 List Webhooks — webhook/list.json

4.3 Get / Delete Webhook — webhook/get.json / webhook/delete.json

5. Suppression List Management

5.1 Add — suppression/set.json

5.2 Check — suppression/get.json

5.3 List — suppression/list.json

5.4 Delete — suppression/delete.json

6. Event Dumps

6.1 Create — event-dump/create.json

6.2 Get / List / Delete

7. Tags — tag/list.json / tag/delete.json

8. Projects — project/create.json / project/list.json

9. System Info — system/info.json

10. Subscribe (Double Opt-In) — email/subscribe.json

Instructions for the Agent

Common Workflows

"Send a test email"

"Check my deliverability setup"

"Validate a list of emails"

"Set up delivery tracking"

Resources

Step 1: Get DNS Record Values — `domain/get-dns-records.json`

Step 2: Verify Domain Ownership — `domain/validate-verification.json`

Step 3: Validate DKIM — `domain/validate-dkim.json`

Step 4: List All Domains — `domain/list.json`

1. Send Email — `email/send.json`

2. Email Validation — `email-validation/single.json`

3.1 Create/Update Template — `template/set.json`

3.2 Get Template — `template/get.json`

3.3 List Templates — `template/list.json`

3.4 Delete Template — `template/delete.json`

4.1 Set Webhook — `webhook/set.json`

4.2 List Webhooks — `webhook/list.json`

4.3 Get / Delete Webhook — `webhook/get.json` / `webhook/delete.json`

5.1 Add — `suppression/set.json`

5.2 Check — `suppression/get.json`

5.3 List — `suppression/list.json`

5.4 Delete — `suppression/delete.json`

6.1 Create — `event-dump/create.json`

7. Tags — `tag/list.json` / `tag/delete.json`

8. Projects — `project/create.json` / `project/list.json`

9. System Info — `system/info.json`

10. Subscribe (Double Opt-In) — `email/subscribe.json`