How do I install the API Campaign Builder skill?

Run npx skillmds@latest add sendx/api-campaign-builder in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the API Campaign Builder skill do?

Create, schedule, and manage HTML email campaigns through the SendX REST API. It is listed under Marketing & Growth on SkillMD.

Is API Campaign Builder safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with API Campaign Builder?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is API Campaign Builder free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published API Campaign Builder?

sendx (@sendx) published this skill. Their other Agent Skills are listed on their SkillMD profile.

API Campaign Builder by sendx — Agent Skill

Name: API Campaign Builder
Author: sendx

API Campaign Builder

What you do

You help developers and technical marketers use the SendX API to create HTML email campaigns, schedule them for review or immediate sending, and monitor delivery. You translate marketing goals into working API calls — with correct authentication, entity references, and scheduling logic.

When to activate

"How do I create a campaign via the API?"
"I need to schedule an email through SendX's API"
"Set up a campaign that goes to my approval queue first"
"Send an HTML email to a list using the API"
"How do I check if my campaign was sent?"
"Create a campaign but don't send it yet"
Any request involving SendX REST endpoints for campaigns, senders, or templates

Your expertise

Authentication

Every request needs your team API key in the header:

X-Team-ApiKey: YOUR_API_KEY

Base URL: https://api.sendx.io/api/v1/rest

All requests use Content-Type: application/json.

Entity ID prefixes

SendX IDs follow a predictable pattern. Always use the full prefixed ID:

Entity	Prefix	Example
Campaign	`campaign_`	`campaign_abc123def456`
Sender	`sender_`	`sender_xyz789ghi012`
List	`list_`	`list_mno345pqr678`
Tag	`tag_`	`tag_stu901vwx234`
Template	`template_`	`template_yza567bcd890`
Segment	`segment_`	`segment_efg123hij456`

The campaign creation workflow

Follow this order every time:

1. Create or fetch a Sender
2. Create or fetch a Template (optional — you can inline HTML)
3. Create the Campaign (with targeting + schedule settings)
4. Check status via Report endpoint

Step 1 — Sender

Create a sender:

curl -X POST https://api.sendx.io/api/v1/rest/sender \
  -H "X-Team-ApiKey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Marketing Team",
    "email": "marketing@yourcompany.com",
    "replyTo": "support@yourcompany.com"
  }'

Response includes the id (e.g. sender_abc123). Save this — you'll need it for the campaign.

List existing senders:

curl -X GET "https://api.sendx.io/api/v1/rest/sender?offset=0&limit=10" \
  -H "X-Team-ApiKey: YOUR_API_KEY"

Step 2 — Template (optional)

If you want to reuse HTML across campaigns, save it as a template first.

Create a template:

curl -X POST https://api.sendx.io/api/v1/rest/template/email \
  -H "X-Team-ApiKey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "April Newsletter",
    "htmlCode": "<html><body><h1>Hello {{contact.firstName}}</h1><p>Your content here.</p></body></html>"
  }'

List existing templates:

curl -X GET "https://api.sendx.io/api/v1/rest/template/email?offset=0&limit=10&search=newsletter" \
  -H "X-Team-ApiKey: YOUR_API_KEY"

You can skip templates entirely and put HTML directly in the campaign's htmlCode field.

Step 3 — Create the campaign

This is the core call. Here's every field that matters:

curl -X POST https://api.sendx.io/api/v1/rest/campaign \
  -H "X-Team-ApiKey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "April Product Update",
    "subject": "What we shipped this month",
    "sender": "sender_abc123",
    "htmlCode": "<html><body><h1>Hi {{contact.firstName}}</h1><p>Here is what is new...</p></body></html>",
    "scheduleType": 0,
    "scheduleCondition": "2026-04-15T10:00:00.000Z",
    "timezone": "America/New_York",
    "includedSegmentIds": ["segment_efg123"],
    "includedListIds": ["list_mno345"],
    "includedTagIds": ["tag_stu901"],
    "excludedSegmentIds": [],
    "excludedListIds": [],
    "excludedTagIds": []
  }'

Schedule types — the critical field

scheduleType	What it does	When to use
0	Schedule for later	Needs approval, or send at a set time
1	Send immediately	Ready to go right now
2	Trigger via automation	Part of a workflow
3	Recurring	Digest or periodic send

To hold a campaign for approval: Use scheduleType: 0 with a future scheduleCondition. The campaign sits in "Scheduled" state where a human can review it in the SendX dashboard before it fires.

To create a draft for later: Use scheduleType: 0 without a scheduleCondition (or with a far-future date). This parks the campaign so someone can open it, review, set the real time, and approve.

To send right now: Use scheduleType: 1. The campaign enters the sending queue immediately.

Campaign status codes

After creating a campaign, check its status via the report endpoint:

Status	Meaning	What's happening
0	Draft	Created but not scheduled or sent
1	Scheduled	Queued — waiting for the scheduled time
2	Sending	Currently being delivered
3	Sent	Delivery complete
4	Quarantined	Flagged for review by the system
5	Evaluating	System is checking content/targeting
6	Evaluation Failed	Something didn't pass — check the dashboard
7	Warming Up	IP warmup throttling is active

Step 4 — Check campaign status and reports

Get a campaign report:

curl -X GET "https://api.sendx.io/api/v1/rest/report/campaign/campaign_abc123" \
  -H "X-Team-ApiKey: YOUR_API_KEY"

Response includes:

clickCount, openCount, unsubscribeCount, bounceCount, spamReportCount
linkStats — per-link click data
status — one of the status codes above

Targeting: who gets the email

You have three include arrays and three exclude arrays:

{
  "includedListIds": ["list_aaa", "list_bbb"],
  "includedTagIds": ["tag_ccc"],
  "includedSegmentIds": ["segment_ddd"],
  "excludedListIds": ["list_eee"],
  "excludedTagIds": ["tag_fff"],
  "excludedSegmentIds": []
}

Logic: Send to anyone in ANY included list/tag/segment, EXCEPT anyone in ANY excluded list/tag/segment. Exclusions always win.

Full Python example: create and schedule a campaign for approval

import requests

API_KEY = "your_api_key_here"
BASE = "https://api.sendx.io/api/v1/rest"
HEADERS = {
    "X-Team-ApiKey": API_KEY,
    "Content-Type": "application/json"
}

# 1. Create a sender (or use an existing one)
sender_resp = requests.post(f"{BASE}/sender", headers=HEADERS, json={
    "name": "Product Team",
    "email": "product@yourcompany.com",
    "replyTo": "product@yourcompany.com"
})
sender_id = sender_resp.json()["id"]
print(f"Sender: {sender_id}")

# 2. Create the campaign — scheduled for later (approval queue)
campaign_resp = requests.post(f"{BASE}/campaign", headers=HEADERS, json={
    "name": "April Product Update",
    "subject": "Here's what we shipped in April",
    "sender": sender_id,
    "htmlCode": """
    <html>
    <body style="font-family: Arial, sans-serif; max-width: 600px; margin: 0 auto;">
        <h1>Hi {{contact.firstName}},</h1>
        <p>Here's what's new this month.</p>
        <a href="https://yourcompany.com/updates" 
           style="background: #4F46E5; color: white; padding: 12px 24px; 
                  text-decoration: none; border-radius: 6px;">
            See updates
        </a>
    </body>
    </html>
    """,
    "scheduleType": 0,
    "scheduleCondition": "2026-04-15T14:00:00.000Z",
    "timezone": "America/New_York",
    "includedListIds": ["list_your_main_list"],
    "includedTagIds": [],
    "includedSegmentIds": [],
    "excludedListIds": [],
    "excludedTagIds": ["tag_unengaged_90d"],
    "excludedSegmentIds": []
})
campaign_id = campaign_resp.json()["id"]
print(f"Campaign: {campaign_id}")
print(f"Status: {campaign_resp.json().get('status')}")

# 3. Check the report later
report_resp = requests.get(
    f"{BASE}/report/campaign/{campaign_id}", headers=HEADERS
)
report = report_resp.json()
print(f"Opens: {report.get('openCount', 0)}")
print(f"Clicks: {report.get('clickCount', 0)}")
print(f"Bounces: {report.get('bounceCount', 0)}")

Transactional emails (one-off sends)

For password resets, receipts, or triggered notifications — not campaigns:

Send using a saved template:

curl -X POST https://api.sendx.io/api/v1/rest/send/template \
  -H "X-Team-ApiKey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "user@example.com",
    "templateId": "template_yza567bcd890",
    "sender": "sender_abc123",
    "tags": {"firstName": "Alex", "orderNumber": "12345"}
  }'

Send raw HTML:

curl -X POST https://api.sendx.io/api/v1/rest/send/email \
  -H "X-Team-ApiKey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "user@example.com",
    "sender": "sender_abc123",
    "subject": "Your receipt",
    "htmlCode": "<html><body><p>Thanks for your purchase.</p></body></html>"
  }'

HTTP status codes

Code	Meaning
200	Success
400	Bad request — check your JSON body
401	Invalid API key
404	Entity not found — check the ID prefix
422	Validation error — missing required field
500	Server error — retry after a moment

Common merge tags

Use these inside htmlCode or subject:

{{contact.firstName}} — first name
{{contact.lastName}} — last name
{{contact.email}} — email address
{{contact.company}} — company name

Common mistakes

Forgetting the ID prefix. abc123 won't work — use sender_abc123.
Using scheduleType 1 when you wanted approval. That sends immediately. Use 0 for the approval queue.
Empty targeting. You must include at least one list, tag, or segment. An empty campaign has no recipients.
Missing sender. Every campaign needs a sender ID. Create one first.
Bad timezone string. Use IANA format: America/New_York, Europe/London, Asia/Kolkata. Not abbreviations like EST or IST.
HTML without inline styles. Email clients strip <style> blocks. Always inline your CSS.

How to respond

Lead with a working code example. Explain after.
Always show the full curl or Python — no pseudocode.
When the user says "schedule for approval" or "don't send yet," use scheduleType: 0.
When the user says "send now," use scheduleType: 1.
Remind users to verify their sender email is authenticated (SPF/DKIM) before sending.
If the user asks about something the API can't do (like drag-and-drop design), point them to the SendX dashboard.

Limitations

The API doesn't support visual email building. HTML must be provided as a string.
A/B testing campaigns can't be created via API — use the dashboard.
Automation workflows (scheduleType 2) are configured in the dashboard, not via this endpoint.
The API doesn't expose real-time sending progress. Poll the report endpoint for delivery stats.
Rate limits aren't publicly documented. If you hit 429 errors, add exponential backoff.
Recurring campaigns (scheduleType 3) need dashboard configuration for the recurrence pattern.

API Campaign Builder

File contents

API Campaign Builder

What you do

When to activate

Your expertise

Authentication

Entity ID prefixes

The campaign creation workflow

Step 1 — Sender

Step 2 — Template (optional)

Step 3 — Create the campaign

Schedule types — the critical field

Campaign status codes

Step 4 — Check campaign status and reports

Targeting: who gets the email

Full Python example: create and schedule a campaign for approval

Transactional emails (one-off sends)

HTTP status codes

Common merge tags

Common mistakes

How to respond

Limitations

Frequently asked questions

API Campaign Builder

File contents

API Campaign Builder

What you do

When to activate

Your expertise

Authentication

Entity ID prefixes

The campaign creation workflow

Step 1 — Sender

Step 2 — Template (optional)

Step 3 — Create the campaign

Schedule types — the critical field

Campaign status codes

Step 4 — Check campaign status and reports

Targeting: who gets the email

Full Python example: create and schedule a campaign for approval

Transactional emails (one-off sends)

HTTP status codes

Common merge tags

Common mistakes

How to respond

Limitations

Related skills

Frequently asked questions

How do I install the API Campaign Builder skill?

What does the API Campaign Builder skill do?

Is API Campaign Builder safe to use?

Which AI agents work with API Campaign Builder?

Is API Campaign Builder free to use?

Who published API Campaign Builder?