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Developer · Transactional API & SMTP Relay

The emails that can’t fail, behind a clean API.

Transactional delivery engineered for independent developers and web agencies. Receipts, password resets, and critical alerts from noreply@ — priced flat per domain, hosted in the EU, with zero AI snooping.

Join the waitlist See the API in action →

EU data storage · REST & SMTP · Instant Sandbox

POST /v1/send

curl -X POST https://api.nilomail.com/v1/send \

-H "Authorization: Bearer nilo_live_9f8a2c1..." \

-H "Content-Type: application/json" \

-d '{

"from": "Bottega Rossi <[email protected]>",

"to": ["[email protected]"],

"subject": "Ordine #4029 confermato",

"html": "<h1>Il tuo lievitato è pronto</h1>"

HTTP/2 200 OK { "id": "msg_01J8F9Q...", "status": "enqueued" }

stream: transactional

[email protected] Delivered in 420ms

MX node: mx.studio.it (TLS 1.3 verify OK)

14:22:08.412

From API key to first delivered email in 3 minutes

Interactive developer walkthrough · 01:15 · No registration required

LIVE RECORDING

4K · STARTTLS · 2048-bit DKIM

Fast onboarding

Three steps to your first production dispatch.

Simple primitives with zero enterprise ritual. Start sending in the time it takes to brew an espresso.

Create scoped key

Generate isolated API credentials for Live or Sandbox. Assign strictly minimal scopes like send:transactional and logs:read.

Scopes: send:tx, logs:read

Verify domain DNS

Add automated DKIM 2048-bit records and your designated Return-Path. Nilomail probes records continuously until green.

• DKIM & SPF valid

Send via REST or SMTP

Target POST /v1/send with JSON payloads or point existing frameworks to smtp.nilomail.com:587 with STARTTLS.

TLS 1.3 / STARTTLS

Security Primitives & Fast Edge

Keys under total developer control.

Granular permission scopes ensure a frontend compromise cannot read webhook payloads or drain your account. Edge routing keeps propagation and delivery fast.

Zero-downtime key rotation with dual overlapping validation.
Instant single-click revocation propagates across all nodes in 50ms.
Strict production CIDR and IP allowlisting for backend origins.

API Credentials

Active tokens for pasticceriarossi.it

nilo_live_9f8a... Live

Scopes: send:transactional, webhooks:read

Used 2m ago

nilo_sand_4b12... Sandbox

Scopes: full_access

Used 1h ago

Production IP Allowlist

198.51.100.24, 203.0.113.88

Traffic originating from unlisted IPs is rejected immediately with HTTP 403 Forbidden.

Registered Webhook Destination

200 OK · 100% last 24h

https://api.pasticceriarossi.it/webhooks/nilomail

Subscribed Event Streams:

X-Nilomail-Signature: sha256=9b7c843da52c81...

{
  "event": "email.delivered",
  "recipient": "[email protected]",
  "message_id": "msg_01J8F9Q9E3A5",
  "stream": "transactional",
  "domain": "pasticceriarossi.it",
  "latency_ms": 420,
  "timestamp": 1774358528
}

Event Loop & Reliability

Signed HMAC webhooks for every single dispatch state.

Connect your system directly to email events without polling. Nilomail delivers structured JSON payloads the exact millisecond an inbox responds, with cryptographic HMAC signatures on every post.

If your server replies with a 5xx status code or times out, our queue initiates exponential backoff retries over 72 hours so no bounce state or receipt confirmation is ever lost.

Real-Time Observability & Legacy SMTP

Logs you can actually debug.

No vague delivery blackholes. Our audit trail exposes complete SMTP handshakes, MX negotiation records, raw headers, and MIME verification states. Dedicated SMTP credentials let you connect legacy frameworks in seconds.

Filter instantly by recipient address, subject, date range, or message-id. Reproduce issues and replay payloads directly to your local development environment with one click.

Native integration with legacy frameworks:

WordPress Rails Django Laravel

Delivered [email protected] · Ordine #4029

14:22:08

Inspection Panel · msg_01J8F9

Return-Path: <[email protected]>

Received-SPF: pass (nilomail.com: domain designates permitted sender)

DKIM-Signature: v=1; a=rsa-sha256; d=pasticceriarossi.it; s=nilo2026;

Authentication-Results: mx.email.it; dkim=pass [email protected]

Dedicated SMTP Relay Credentials

Zero code rewrite for existing WordPress, Rails, Django, and Laravel codebases

Host: smtp.nilomail.com Port: 587 (STARTTLS) or 465 (SSL/TLS)

pasticceriarossi.it

Verified

Custom Return-Path: bounces.pasticceriarossi.it

2048-bit DKIM Key

Transactional

Receipts, security auth, and order alerts. Dedicated high-reputation pipe with zero queue sharing.

Priority 10 · 99.98% Inbox

Conversational

Newsletters and team broadcasts. Isolated pool ensures sudden spam reports never delay critical password resets.

Isolated IP pool

Domain Integrity & Stream Separation

Clean reputation, fully ring-fenced.

Your transactional receipts should never suffer because a seasonal marketing broadcast had unsubscribes. Nilomail isolates delivery streams at the protocol level.

Automated DKIM key rotation, automated DMARC compliance monitoring, and custom Return-Path domains ensure recipient mailboxes recognize your genuine brand identity from day one.

Engineered For Client Work

One workspace per client. One place to look when an email doesn’t arrive.

Designed specifically for digital studios, web developers, and freelance agencies managing multiple client stacks. No shared keys, no cross-domain pollution.

CLIENT WORKSPACES Agency Master: Studio Alpha Milano

Pasticceria Rossi Milano Pristine

pasticceriarossi.it · 12.4k dispatches this month

Active

Studio Moretti Architetti Pristine

studiomoretti.eu · 3.1k dispatches this month

Bottega Legno Artigiana Pristine

bottegalegno.it · 890 dispatches this month

Independent billing attribution

Charge credit cards directly per client or roll costs into your agency retainer automatically.

Isolated domain reputations

A misconfigured template on one client never spills over to affect your other clients.

1-click ownership handover

Easily invite your client’s internal admin to assume billing and DNS controls when your retainers end.

Unified River Suite

Everything your client needs, in one service.

Stop stitching together three different vendors with three different invoices.

Mailbox Workspace

Personal addresses and unified shared inboxes (ciao@, info@) with assignments, internal notes, and response SLAs.

Explore Mailbox →

Campaigns Workspace

Double opt-in subscriber management, verified consent logging, and tranquil email broadcast tools built with GDPR at heart.

Explore Campaigns →

Developer Workspace

Current

Transactional REST API, SMTP relay endpoint, high-precision webhooks, and granular security keys under your own domain.

You are here

Architectural Comparison

Nilomail Developer vs Sending-Only Email APIs

Why independent studios choose a calm, unified stack instead of disconnected micro-services.

Feature capability

Nilomail

Dedicated Sending-Only API

Mailboxes & Shared Inbox

Included in same account

No (requires Google Workspace + Zendesk)

Newsletters & Consent Log

Native Campaigns workspace

No (requires Mailchimp or Brevo)

Per-Client Agency Workspaces

Native multi-tenant isolation

Complex sub-accounts & shared billing

Data stored in the EU

Stored in the EU

Varies by vendor and plan

Transparent Economics

Which plan fits your volume?

Move the sliders to see which Nilomail plan covers your automated emails and domains. Mailbox email is separate and unlimited for normal use.

Automated emails per month (campaigns + API): 10,000 / mo

1k 10k 25k 50k+

Number of domains: 3 domains

1 3 5 10

Recommended plan

€12

/month, billed monthly

Billed yearly

€120

/year (save 17%)

Included in this plan: Automated emails/mo: 10,000 · Domains: 3 · Users: 5

When a sending-only service is better:

If your application exclusively requires raw ultra-high volume bulk broadcasting (e.g. 5M+ emails daily) without any need for human customer mailboxes, domain consolidation, or client management, a pure dedicated bulk pipe may fit your specific scale.

Answers for Engineers

Frequently asked questions.

Can I use the SMTP relay to read incoming emails?

No. The SMTP relay endpoint is strictly for outbound delivery. Incoming emails are directed directly into your Nilomail Mailbox workspace for your team or forwarded as webhook events if you configure inbound routing rules.

What is the difference between Sandbox and Live environments?

Sandbox keys route deliveries into an internal developer blackhole. We simulate real SMTP round-trips, validate authentication, update the inspector logs, and trigger test webhooks without ever attempting delivery to the destination MX server. Live keys touch real world inbox infrastructure.

Can I manage multiple client accounts under one developer login?

Yes. You maintain a single master studio login. Each client domain lives in its own sandboxed workspace with dedicated API keys, distinct DNS verification status, independent webhook endpoints, and separated billing preferences.

How do I migrate transactional mail from Amazon WorkMail or legacy SMTP?

Update your outbound SMTP hostname to smtp.nilomail.com on port 587 with STARTTLS (or swap to our REST API), update your domain SPF record to include our mechanism, and add our 2048-bit DKIM records. Existing templates require zero formatting changes.

How does signed HMAC webhook verification work?

Every webhook payload includes an X-Nilomail-Signature HTTP header generated with HMAC-SHA256 using your webhook signing secret. You calculate sha256(secret, rawBody) on incoming requests and compare in constant time.

Relevant guides & adjacent workspaces

View all guides →

Migration

Clean code. Pristine delivery. Zero bloat.

Set up your first domain, grab your API credentials, and start transmitting production transactional mail in under five minutes.

Data stored in the EU · Zero artificial intelligence models trained on your payloads or logs