Sendr365 Developer Documentation

Sendr365 is a multi-channel email infrastructure platform — transactional API, SMTP relay, marketing campaigns, contact management, and webhook events. This guide walks you from a first API call to production sending.

Every endpoint accepts JSON over HTTPS. Authentication is via a tenant API key (X-API-Key header) — generated in your dashboard. All paths are versioned under https://sendr365.com/api/v1.

What's in here

• Quick start
• Authentication
• Send an email
• Campaigns
• Contacts
• Domains
• SMTP relay
• Webhooks
• Errors & limits

Three steps: sign up, generate an API key, send a test email. No credit card required — every new account gets 100 free emails for 30 days — 50 transactional + 50 marketing.

curl -X POST 'https://sendr365.com/api/v1/email/send' \
  -H 'X-API-Key: YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "to": "[email protected]",
    "subject": "Hello from Sendr365",
    "html": "<h1>It works!</h1><p>This is your first email.</p>"
  }'

Response

{
  "sent": 1,
  "skipped": 0,
  "failed": 0,
  "results": [
    { "to": "[email protected]", "messageId": "msg_2K9xQz3vN8mLp4yF", "status": "sent" }
  ],
  "creditsRemaining": 99
}

Tenant endpoints are authenticated with an API key in the X-API-Keyheader. Each key is scoped to one account — keep keys server-side, never embed in browser code.

API key scopes

Every key has a set of scopes. Pick the minimum scope your integration needs — narrower scopes reduce blast radius if a key leaks.

Header format

X-API-Key: sk_live_AbCdEf123456...

Rate limits

Default rate limit: 10 requests/sec per key, with burst tolerance. Hit a limit → 429 Too Many Requests with a Retry-Afterheader. Upgrade plans raise the ceiling.

The POST /email/send endpoint sends one transactional email synchronously. Use it for OTP codes, password resets, receipts, alerts — anything triggered by a single user action.

When to use this

• One-off, system-generated emails to a single recipient
• Time-sensitive sends (login codes, order confirmations)
• Emails triggered programmatically from your backend

Request body

Code examples

curl -X POST 'https://sendr365.com/api/v1/email/send' \
  -H 'X-API-Key: $SENDR365_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "to": "[email protected]",
    "subject": "Your order #1234 is confirmed",
    "html": "<h1>Thanks Alice!</h1><p>Your order ships tomorrow.</p>",
    "fromEmail": "[email protected]",
    "fromName": "Acme Store"
  }'

Response

{
  "sent": 1,
  "skipped": 0,
  "failed": 0,
  "results": [
    { "to": "[email protected]", "messageId": "msg_2K9xQz3vN8mLp4yF", "status": "sent" }
  ],
  "creditsRemaining": 99
}

Batch sending

To send many transactional emails in one request, post { "messages": [...] } with up to 500 message objects, each with the same fields shown above. Credits are debited atomically for the whole batch up-front.

Campaigns send the same email to many recipients with throttling, suppression filtering, and per-recipient tracking. Use these for newsletters, broadcasts, and re-engagement flows.

Lifecycle

• Create a draft (subject, sender, body)
• Schedule it against one or more lists
• Worker expands the audience and dispatches at your configured rate
• Each recipient deducts 1 marketing credit

Create + schedule

# 1. Create draft
curl -X POST 'https://sendr365.com/api/v1/campaigns' \
  -H 'X-API-Key: $SENDR365_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "name": "April newsletter",
    "subject": "What we shipped this month",
    "fromEmail": "[email protected]",
    "fromName": "Acme Team",
    "bodyHtml": "<h1>Hello!</h1><p>...</p>"
  }'

# 2. Schedule it (returns campaignId)
curl -X POST 'https://sendr365.com/api/v1/campaigns/CAMPAIGN_ID/schedule' \
  -H 'X-API-Key: $SENDR365_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{ "listIds": ["list_abc"], "scheduledFor": "2026-05-01T10:00:00Z" }'

Contacts are people you can send to. Lists are groups of contacts. Suppressions are global — a contact who unsubscribes won't receive any future marketing send from your account.

Add contacts to a list

curl -X POST 'https://sendr365.com/api/v1/contacts' \
  -H 'X-API-Key: $SENDR365_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "email": "[email protected]",
    "firstName": "Alice",
    "lastName": "Smith",
    "tags": ["vip"],
    "listIds": ["list_abc"]
  }'

Add a domain you own, publish 3 DNS records (SPF, DKIM, DMARC), and Sendr365 auto-verifies within ~5 minutes. The default [email protected] identity is provisioned the moment verification completes.

Add domain

curl -X POST 'https://sendr365.com/api/v1/sending-domains' \
  -H 'X-API-Key: $SENDR365_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{ "domain": "yourdomain.com", "selector": "mf1" }'

Response

{
  "id": "dom_2KP4...",
  "domain": "yourdomain.com",
  "spfStatus": "PENDING",
  "dkimStatus": "PENDING",
  "dmarcStatus": "PENDING",
  "dnsRecords": {
    "spf":   { "host": "yourdomain.com",     "type": "TXT", "value": "v=spf1 include:..." },
    "dkim":  { "host": "mf1._domainkey...",  "type": "TXT", "value": "..." },
    "dmarc": { "host": "_dmarc.yourdomain.com", "type": "TXT", "value": "v=DMARC1; p=none; ..." }
  }
}

Publish the records at your registrar, then poll GET /sending-domains/:id— or just wait, the platform auto-checks every 3 minutes. Status flips through PENDING → CHECKING_DNS → VERIFYING_PROVIDER → ACTIVE.

Already using a tool that speaks SMTP? Point it at our relay and you're done — no API integration needed. Works with WordPress, Shopify, n8n, Zapier, and any custom backend.

Generate credentials

Open SMTP settings in your dashboard, click Generate credentials, and copy both the username + password. Each credential is independent — you can have one per integration.

Node.js (Nodemailer)

import nodemailer from 'nodemailer';

const transporter = nodemailer.createTransport({
  host: 'smtp.sendr365.com',
  port: 587,
  secure: false,        // STARTTLS upgrades the connection
  requireTLS: true,
  auth: {
    user: process.env.SENDR_SMTP_USER,
    pass: process.env.SENDR_SMTP_PASS,
  },
});

await transporter.sendMail({
  from: '"Acme" <[email protected]>',
  to: '[email protected]',
  subject: 'Order confirmed',
  html: '<p>Thanks!</p>',
});

Outbound webhooks are on the roadmap — Sendr365 will POST real-time events (opens, clicks, bounces, complaints, unsubscribes) to a URL you control. Until that's live, use the polling endpoints below or the dashboard Metrics page.

Today: see events in the dashboard

Events are tracked internally and surfaced in the Metrics dashboard with per-campaign breakdowns. A read API + push webhooks are next on the roadmap.

Event types tracked

What's coming

• POST your endpoint a JSON payload per event with HMAC-SHA-256 signature
• Configurable retry policy (exponential backoff, 24-hour give-up)
• Dashboard UI to register endpoints and inspect delivery history
• Per-event-type filtering so you only get the events you care about

Want webhooks now? Open a ticket at /app/support — we prioritize based on user demand.

Errors return JSON with a stable error code your client can branch on. Always check status codes — 2xx = success, 4xx = your fault, 5xx = ours.

Error response format

{
  "statusCode": 400,
  "error": "INSUFFICIENT_CREDITS",
  "message": "Need 50 marketing credits; have 12 free + 0 paid",
  "have": { "free": 12, "paid": 0 },
  "category": "PROMO"
}

Common error codes

Codes in bold are stable — your client can safely branch on them. Others come from the framework's default HTTP error mapping.

Rate limit windows