How it Works

From `sendMail()` to
their inbox — and back.

Eight stages, one endpoint, every event logged. Below is the full journey — how one line of SMTP code becomes a verified, ISP-routed, provider-diversified send with a reply that comes back as a parsed contact.

Start free See the pricing

Live pipeline · smtp.sendrules.net

Send

Verify

Route

Send

Land

Harvest

Verified · Routed · Delivered · Reply parsed← 8 stages in ≤ 240ms typical

How it works

Eight stages between your `sendMail()` and their inbox.

Verified, routed, delivered — then replies harvested for contacts you would otherwise lose.

Your app

Any SMTP client, any framework.

Node · Python · Ruby · Go · PHP · curl

SMTP ingress

smtp.sendrules.net, TLS on both submission ports.

Password auth over TLSIP allow-listReal Let's Encrypt cert

Quality gate

Every recipient scored in the send path, before your provider sees them.

SyntaxSuppressionDisposableRoleTypoLive SMTP

Grid & Rules

Pick a strategy. Fail over automatically.

RRWeightedPriorityRandomStickyMX-ISP

Provider fleet

Your accounts. Your reputation. Your quota.

SESSendGridPostmarkMailgun+11 more

Recipient MX

Gmail, Yahoo, Outlook, Apple, or anywhere else.

DeliveryBounceComplaintReplyOOO

Autoresponder parser

Turns OOO replies into contact lists — new colleagues, referrals, forwarded contacts.

Harvest emailsRegex fieldsIgnore listWebhookCSV export

Signals & control

Everything logged, signed, and searchable.

Signed webhooks7-inbox ActivityDMARC monitorPostmaster

Every step logged with reason codesSigned, verifiable webhooks with replay4-tier limits — queue, don't dropDMARC + blocklist + Postmaster in one view

Your app
01
Any SMTP client, any framework.
Node · Python · Ruby · Go · PHP · curl
SMTP ingress
02
smtp.sendrules.net, TLS on both submission ports.
Password auth over TLSIP allow-listReal Let's Encrypt cert
Quality gate
03
Every recipient scored in the send path, before your provider sees them.
SyntaxSuppressionDisposableRoleTypoLive SMTP
Grid & Rules
04
Pick a strategy. Fail over automatically.
RRWeightedPriorityRandomStickyMX-ISP
Provider fleet
05
Your accounts. Your reputation. Your quota.
SESSendGridPostmarkMailgun+11 more
Recipient MX
06
Gmail, Yahoo, Outlook, Apple, or anywhere else.
DeliveryBounceComplaintReplyOOO
Autoresponder parser
07
Turns OOO replies into contact lists — new colleagues, referrals, forwarded contacts.
Harvest emailsRegex fieldsIgnore listWebhookCSV export
Signals & control
08
Everything logged, signed, and searchable.
Signed webhooks7-inbox ActivityDMARC monitorPostmaster

See it in action

Prefer to watch? The same eight stages, in two minutes.

The walkthrough follows one message the whole way down the diagram above — verified, routed by real MX, delivered through your own provider, and back again as a parsed contact. It is silent-safe, so you can watch it in an open-plan office.

Watch with the scene-by-scene breakdown

01Connect

One SMTP endpoint. Every language.

Point any SMTP client at smtp.sendrules.net. TLS on both submission ports, real Let’s Encrypt certificate, no self-signed workarounds. Every credential can be locked to a specific list of network ranges — a leaked password from outside your infrastructure cannot authenticate, even with the correct value.

Works with any SMTP client — no SDK, no proprietary protocol, no vendor lock-in
Credentials one per rule, so different traffic classes never share a queue
Rotate the password from the UI — the old one stops working immediately

import nodemailer from "nodemailer";

const t = nodemailer.createTransport({
  host: "smtp.sendrules.net",
  port: 587,
  secure: false,           // STARTTLS negotiated in-band
  auth: {
    user: process.env.SENDRULES_USER,   // per rule
    pass: process.env.SENDRULES_PASS,
  },
});

await t.sendMail({
  from: "[email protected]",
  to: "[email protected]",
  subject: "Your order #1042 is on its way",
  html: renderOrderEmail(order),
});

Verifying · 4 recipientsBudget · 2.0s

Syntaxpass
Standards-conformant address parsing, international-domain safe
Suppression listpass
Your workspace list + your bounce history, checked together
Disposable domainreject
Refreshed daily against curated + community feeds
Role accountflag
info@ / admin@ / postmaster@ — flag or reject per policy
Typo domainflag
gmial.com → gmail.com — corrected before send
Live SMTP checkpass
Confirms the mailbox exists at the recipient's mail server

accepted

flagged

rejected

03Verify

Six checks in the send path.

Before the message ever leaves for a provider, every recipient is scored — in the send path itself, on a two-second budget. Bad addresses never spend your ESP quota. Risky ones are flagged. The policy is per rule, so you can reject on outbound cold email and only flag on transactional.

A live mailbox check against the recipient’s mail server, routed through our secure probe network
A workspace-wide bounce history that catches recycled spam-trap addresses across tenants
A tiered cache (valid 30 days, invalid 90, catch-all 14) so the same address is never probed twice

See how the Quality Gate works

04Route

Six routing strategies. Coverage warnings built in.

Every rule picks a strategy. The rule editor tells you which ISPs your attached providers cover — and warns before you save if there’s a Yahoo-shaped gap.

Round-robin

Rotate through every attached provider evenly. Simple, predictable, hard to hurt yourself with.

Weighted

Assign a percentage per provider. 70% through SES, 25% through Postmark, 5% through the fallback.

Priority

Try provider one; if it errors, try provider two; and so on. The classical failover pattern.

Random

Uniform-random pick — useful for A/B testing two providers on identical traffic.

Sticky sender

First delivery to a recipient pins a sender. Every follow-up uses that same sender — reply-rate stays clean.

ISP

MX-based ISP

Resolve the recipient's live MX record. Gmail buyer → your Gmail-friendly provider; Yahoo → your Yahoo-friendly one.

See how Grid & Rules works

05Send

Your accounts. Your reputation. Your quota.

sendrules holds your provider credentials encrypted per tenant, but never bills you for the mail — the send goes through your account with your provider. When one provider rate-limits or errors, the next attached provider picks up automatically.

Amazon SESok

1,842sent · last min

SendGridrate-limited

204sent · last min

Postmarkok

963sent · last min

Priority strategy — SendGrid returned 429, sendrules rerouted to Postmark on the same rule with no bounce, no drop.

06Land

Delivered — and classified by the real ISP.

We resolve the recipient’s live MX record, so “[email protected]” that fronts on Google Workspace is correctly routed as a Gmail recipient. Every provider webhook is normalized into the same event shape — delivered, bounced, complained, deferred — with the underlying provider preserved for drilldown.

MX-based classification catches domains that front on Google Workspace or Microsoft 365
Provider webhooks normalized to one event shape — no per-vendor branching in your app
Deferred sends land back in the queue with a retry-at timestamp; no dropped mail

Last 24h · classified by MX52,481 messages

Gmail62%
Outlook / Hotmail18%
Yahoo9%
Apple iCloud6%
AOL2%
Other3%

MX-based— we resolve the recipient’s live MX record, so “[email protected]” that fronts on Google Workspace is correctly counted as Gmail.

Autoresponder harvest

Every OOO reply is a contact. Most senders throw them away.

Ten to twenty percent of campaign replies are autoresponders — and most of them carry the exact contact info you were trying to reach: “I’m on leave until Monday, please contact [email protected] for procurement questions.” sendrules parses every one, harvests every address, captures every named field, and drops the result into a list you can trigger a webhook from or download as CSV.

Harvest emails
Every address inside the body is extracted — new colleagues, forwards, referrals, procurement contacts.
Named field capture
Regex rules pull structured data — a name after 'Please contact', a phone number, an alternate ID.
Ignore list
Skip your own domain, common noise, and addresses you already have. Nothing duplicated, nothing polluted.
Webhook or CSV
Push new contacts into your CRM in real time, or download the list on demand.

See the parser in the product See the pricing →

Inbound reply · 08:14 UTCAutoresponder · OOO

From: [email protected]

Subject: Automatic reply: Q4 vendor request

Thanks for your note — I’m on parental leave until 15 January 2026. For procurement, please reach [email protected]. Legal + contracts: [email protected] (direct: +44 20 7946 0123).

Parser: rule "acme-tier1" · list "acme-warm" · 3 new contacts

Contact list · acme-warm

1,247 totalExport CSV

Webhook · POST200 OK

{
  "event": "parser.contact",
  "list": "acme-warm",
  "email": "[email protected]",
  "fields": {
    "role": "procurement",
    "return_date": "2026-01-15"
  },
  "source_msg": "01f9...abcd",
  "ts": "2026-11-04T08:14:32Z"
}

Activity · live

AllDeliveredBounced

14:02:11delivered[email protected]Amazon SES
14:02:11delivered[email protected]Postmark
14:02:10opened[email protected]Amazon SES
14:02:09deferred[email protected]SendGrid → Postmark
14:02:08delivered[email protected]SES
14:02:07bounced[email protected]quality gate
14:02:06replied[email protected]inbound
14:02:05delivered[email protected]Postmark

98.2%

Delivery rate

0.4%

Bounce

0.02%

Complaint

08Observe

Every message, every step, every reason.

Seven filtered activity inboxes. Row-level trend sparklines. Period-comparison cards. Share links that make any filtered slice a read-only URL you can send to your team. Behind it all: a normalized event stream your webhooks subscribe to — signed, verifiable, and replayable from the UI when something needs a second run.

Full deliverability suite alongside — DMARC compliance %, blocklist, Postmaster, seed placement
Saved views + column picker + keyboard shortcuts so Activity behaves like an inbox, not a report
Audit log on every operator action — RBAC-gated, regulator-ready

Under the flow

Six guarantees that hold under every stage.

TLS on submission with a real certificate — no self-signed workaround

Credentials scoped to your network ranges, not just to a password

Message content encrypted at rest, per tenant

Every stage logged with a reason — auditor-ready

Signed, verifiable webhooks with retries and one-click replay

Four-tier limits — we queue instead of dropping, released at midnight UTC

See the pipeline running against your own traffic.

Free plan — 5,000 messages/month, every feature on this page included. Attach one provider and watch the flow light up in the Activity view.

Start free See the pricing

One SMTP endpoint. Every language.

Works with any SMTP client — no SDK, no proprietary protocol, no vendor lock-in

Credentials one per rule, so different traffic classes never share a queue

Rotate the password from the UI — the old one stops working immediately

import nodemailer from "nodemailer"; const t = nodemailer.createTransport({ host: "smtp.sendrules.net", port: 587, secure: false, // STARTTLS negotiated in-band auth: { user: process.env.SENDRULES_USER, // per rule pass: process.env.SENDRULES_PASS, }, }); await t.sendMail({ from: "[email protected]", to: "[email protected]", subject: "Your order #1042 is on its way", html: renderOrderEmail(order), });

Six checks in the send path.

A live mailbox check against the recipient’s mail server, routed through our secure probe network

A workspace-wide bounce history that catches recycled spam-trap addresses across tenants

A tiered cache (valid 30 days, invalid 90, catch-all 14) so the same address is never probed twice

See how the Quality Gate works

Delivered — and classified by the real ISP.

MX-based classification catches domains that front on Google Workspace or Microsoft 365

Provider webhooks normalized to one event shape — no per-vendor branching in your app

Deferred sends land back in the queue with a retry-at timestamp; no dropped mail

Every OOO reply is a contact. Most senders throw them away.

Harvest emails

Every address inside the body is extracted — new colleagues, forwards, referrals, procurement contacts.

Named field capture

Regex rules pull structured data — a name after 'Please contact', a phone number, an alternate ID.

Ignore list

Skip your own domain, common noise, and addresses you already have. Nothing duplicated, nothing polluted.

Webhook or CSV

Push new contacts into your CRM in real time, or download the list on demand.

{ "event": "parser.contact", "list": "acme-warm", "email": "[email protected]", "fields": { "role": "procurement", "return_date": "2026-01-15" }, "source_msg": "01f9...abcd", "ts": "2026-11-04T08:14:32Z" }

Every message, every step, every reason.

Full deliverability suite alongside — DMARC compliance %, blocklist, Postmaster, seed placement

Saved views + column picker + keyboard shortcuts so Activity behaves like an inbox, not a report

Audit log on every operator action — RBAC-gated, regulator-ready

From sendMail() totheir inbox — and back.

Eight stages between your sendMail() and their inbox.

Your app

SMTP ingress

Quality gate

Grid & Rules

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Your app

SMTP ingress

Quality gate

Grid & Rules

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Prefer to watch? The same eight stages, in two minutes.

One SMTP endpoint. Every language.

Six checks in the send path.

Six routing strategies. Coverage warnings built in.

Round-robin

Weighted

Priority

Random

Sticky sender

MX-based ISP

Your accounts. Your reputation. Your quota.

Delivered — and classified by the real ISP.

Every OOO reply is a contact. Most senders throw them away.

Every message, every step, every reason.

Six guarantees that hold under every stage.

See the pipeline running against your own traffic.

From sendMail() totheir inbox — and back.

Eight stages between your sendMail() and their inbox.

Your app

SMTP ingress

Quality gate

Grid & Rules

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Your app

SMTP ingress

Quality gate

Grid & Rules

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Prefer to watch? The same eight stages, in two minutes.

One SMTP endpoint. Every language.

Six checks in the send path.

Six routing strategies. Coverage warnings built in.

Round-robin

Weighted

Priority

Random

Sticky sender

MX-based ISP

Your accounts. Your reputation. Your quota.

Delivered — and classified by the real ISP.

Every OOO reply is a contact. Most senders throw them away.

Every message, every step, every reason.

Six guarantees that hold under every stage.

See the pipeline running against your own traffic.

From `sendMail()` to
their inbox — and back.

Eight stages between your `sendMail()` and their inbox.

From `sendMail()` to
their inbox — and back.

Eight stages between your `sendMail()` and their inbox.