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Send your first transactional email.

Create a verified domain, generate an API key, and send only after Milesender marks the domain production ready. Every project starts in sandbox, so you can build the whole integration before DNS is even in the picture.

Quickstart

1. Create a workspace. You get a sandbox sender immediately, no domain required.
2. Send a test email with your ms_test_ key to confirm the integration works end to end.
3. Add your sending domain and add the generated SPF, DKIM, DMARC, and return-path records at your DNS provider.
4. Wait for verification. Milesender polls your DNS and flips the domain to verified automatically.
5. Swap in a live key (ms_live_) or SMTP credential and you're sending production email.

API setup

One endpoint handles every send. Authenticate with a bearer token — use a sandbox key while you build, swap in a live key once your domain is verified.

POST /v1/emails

curl https://api.milesender.com/v1/emails \
  -H "Authorization: Bearer ms_live_xxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "Milesender <hello@example.com>",
    "to": ["user@gmail.com"],
    "subject": "Welcome to Milesender",
    "html": "<h1>Hello</h1>",
    "text": "Hello"
  }'

SMTP setup

Any language or platform with an SMTP client works without a Milesender library — point it at these settings using a generated SMTP credential.

Host

smtp.milesender.com

Port

587 (STARTTLS) or 465 (TLS)

Username

ms_smtp_xxxxx

Password

generated with the credential

Domain verification

Add a domain from Dashboard → Domainsand Milesender generates four DNS records scoped to that domain. Verification is automatic — Milesender polls your DNS provider and flips each record's status as it resolves, no manual "check now" step required in production.

TXTProves you control the domain and authorizes Milesender to send from it (SPF).

TXTSigns every outbound message so receiving servers can verify it wasn't altered (DKIM).

TXTTells inboxes what to do with mail that fails authentication (DMARC).

CNAMERoutes bounce and complaint notifications back to Milesender.

SPF/DKIM/DMARC

All three exist to answer the same question for a receiving inbox: was this email actually sent by who it claims to be from? Milesender requires all three before unlocking production sending, because passing only one or two is exactly the gap spammers exploit.

SPF — a list of servers allowed to send mail for your domain. Milesender adds itself to yours.
DKIM — a cryptographic signature on every message, so a receiving server can detect if it was tampered with in transit.
DMARC — the policy that tells inboxes what to do when SPF or DKIM fails: quarantine, reject, or (during rollout) do nothing and just report it.

Webhooks

Subscribe an endpoint from Dashboard → Webhooks and Milesender POSTs a signed JSON payload for every event you select.

email.sentemail.deliveredemail.bouncedemail.complainedemail.openedemail.clickeddomain.verifieddomain.failed

payload.json

{
  "type": "email.delivered",
  "created_at": "2026-07-15T14:02:08Z",
  "data": {
    "id": "email_01JZ9G2Q",
    "to": "user@gmail.com",
    "from": "hello@example.com",
    "subject": "Welcome to Milesender"
  }
}

Errors

Every error response includes a stable `code` you can match on in code, not just an HTTP status.

Status	Code	Meaning
400	invalid_request	A required field is missing or malformed. The response body names the field.
401	invalid_api_key	The key is missing, revoked, or doesn't match the environment (test vs. live).
403	domain_not_verified	You're sending from a domain that hasn't passed SPF/DKIM/DMARC verification yet.
422	invalid_recipient	The `to` address failed basic syntax validation before Milesender queued the send.
429	rate_limited	You've exceeded your plan's requests-per-second limit. Retry after the `Retry-After` header.
500	internal_error	Something failed on Milesender's side. Safe to retry with backoff.

Rate limits

Limits are per credential, not per workspace, so a busy sandbox key never affects your production sending.

Credential	Requests	Volume
Sandbox key (ms_test_)	10 requests / second	100 emails / day
Live key (ms_live_)	50 requests / second	Plan-based, see billing
SMTP (ms_smtp_)	20 connections / second	Plan-based, see billing

Node.js

send.ts

import { Milesender } from "@milesender/node";

const milesender = new Milesender(process.env.MILESENDER_API_KEY);

await milesender.emails.send({
  from: "Milesender <hello@example.com>",
  to: "user@gmail.com",
  subject: "Welcome",
  html: "<p>Your account is ready.</p>",
});

Next.js

Call the API from a route handler so your API key never reaches the client.

app/api/welcome/route.ts

import { Milesender } from "@milesender/node";

const milesender = new Milesender(process.env.MILESENDER_API_KEY);

export async function POST(request: Request) {
  const { email } = await request.json();

  await milesender.emails.send({
    from: "Milesender <hello@example.com>",
    to: email,
    subject: "Welcome",
    html: "<p>Your account is ready.</p>",
  });

  return Response.json({ ok: true });
}

Laravel

Drop an SMTP credential into your mail config — Laravel's mailer needs no Milesender-specific package.

.env

MAIL_MAILER=smtp
MAIL_HOST=smtp.milesender.com
MAIL_PORT=587
MAIL_USERNAME=ms_smtp_xxxxx
MAIL_PASSWORD=your_smtp_password
MAIL_ENCRYPTION=tls
MAIL_FROM_ADDRESS="hello@example.com"

Python

send.py

from milesender import Milesender

milesender = Milesender("ms_live_xxxxx")

milesender.emails.send(
    from_="Milesender <hello@example.com>",
    to="user@gmail.com",
    subject="Welcome",
    html="<p>Your account is ready.</p>",
)

Go

send.go

client := milesender.NewClient("ms_live_xxxxx")

_, err := client.Emails.Send(ctx, &milesender.SendRequest{
    From:    "Milesender <hello@example.com>",
    To:      "user@gmail.com",
    Subject: "Welcome",
    Html:    "<p>Your account is ready.</p>",
})