Source Code

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

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