One SMTP endpoint.
Every provider.
Verified before the send.
Autoresponders parsed for contacts.

sendrules is a multi-tenant SMTP proxy that routes across your existing providers, blocks bad recipients in the send path, harvests contacts from autoresponder replies, and gives you the deliverability tooling most vendors sell separately.

Start free See a live route log

sendrules · pipeline

how it works

Your appany SMTP client

NodePythonRubyGo

SMTP ingresssmtp.sendrules.net

587 STARTTLS465 implicitIP allow-list

Quality gate6 checks

SyntaxSuppressionDisposableRoleTypoReacher

Grid router6 strategies

RRWeightedPriorityStickyMX-ISP+ ramp-up

Provider fleet15 providers

SESSendGridPostmarkMailgun+11

Recipient inboxdelivery + replies

GmailYahooOutlookAppleOther

Autoresponder parserOOO → contacts

HarvestRegex fieldsIgnoreWebhookCSV

Signals & controlobservability

DMARCPostmasterBlocklistsHMAC webhooksActivity

providers supported end-to-end

routing strategies, one endpoint

verification checks in the SMTP DATA phase

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, 587 STARTTLS + 465 implicit.

AUTH LOGIN/PLAINIP allow-listReal LE cert

Quality gate

Every recipient scored in the DATA phase.

SyntaxSuppressionDisposableRoleTypoReacher

Grid router

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.

HMAC webhooks7-inbox ActivityDMARC ruaPostmaster

Every step logged with reason codesHMAC-signed 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, 587 STARTTLS + 465 implicit.
AUTH LOGIN/PLAINIP allow-listReal LE cert
Quality gate
03
Every recipient scored in the DATA phase.
SyntaxSuppressionDisposableRoleTypoReacher
Grid router
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.
HMAC webhooks7-inbox ActivityDMARC ruaPostmaster

The problem

Sending isn’t a provider problem. It’s a routing problem.

Every ESP has an incident window, a throttle policy, and a reputation you don’t fully control. Locking yourself to one of them means one bad afternoon takes your transactional stream with it. sendrules sits in front of the providers you already trust and turns them into a fleet with observable routing, per-recipient verification, and shared deliverability tooling.

Bring your own

Bring the providers you already trust. We don’t resell sending.

Attach SES, SendGrid, Postmark, Mailgun, SparkPost, Brevo, Resend, Mailjet, Elastic, SMTP2GO, Zoho, Google Workspace, O365, Mailcrux, or any custom SMTP. Keep their pricing. Keep their warmed IPs. Keep the sender reputation you’ve spent years building. sendrules adds routing, verification, and observability without asking you to migrate a single domain.

AWS SESAPISendGridMailgunAPIPostmarkSparkPostAPIBrevoResendMailjetElastic EmailSMTP2GOZoho ZeptoMailGoogle WorkspaceOffice 365MailcruxCustom SMTP

Compatible with the providers you already use — bring your own credentials, keep your reputation.

Headline capability

Verify recipients before the send, not after the bounce.

Every recipient runs through syntax parsing, suppression lookup, disposable-domain detection, role-address flagging, typo correction, and Reacher SMTP-level verification — inside the DATA phase, before your provider ever sees the address. Bounces you would have paid for become route logs you can act on. List decay becomes visible instead of expensive.

Executed in-band; no pre-flight API call to remember
Per-check block reasons written to the recipient's route log
Rejected recipients do not count against monthly volume

Quality gate — RCPT

[email protected]

Syntaxvalid

Suppressionclean

Disposable domainnot listed

Role accountn/a

Typo detectiondid you mean example.com?

SMTP probedomain does not exist

550 5.1.2 recipient rejected · typo suggested · not counted against volume

Grids

Six routing strategies, one endpoint.

A Grid is a named routing rule with any number of providers attached. Pick round-robin, weighted, priority, random, sticky-sender, or MX-based ISP routing. Coverage warnings tell you which mailbox providers a Grid can actually reach before you save it. Temporary provider errors trigger automatic failover without touching your application code.

Round-robin, weighted, priority

Spread load evenly, distribute by weight, or fall through by priority until a provider accepts. Failover on temporary errors is automatic.

Sticky-sender

Pin every recipient to the first provider that delivered to them. Improves inbox placement over the second week without any manual list segmentation.

MX-based ISP routing

Resolve each recipient's live MX record and route on that — so vanity domains on Google Workspace or O365 land in the right ISP lane every time.

MX-based classification

Route by the recipient’s real mail server.

Domain-string classification breaks the moment a customer moves acme.com to Google Workspace or O365. sendrules resolves the recipient’s live MX record and routes on that — so vanity domains land in the right ISP lane and your Gmail-tuned provider actually handles Gmail-hosted mail.

Deliverability suite

Deliverability tooling, alongside the sending it belongs to.

Aggregate ruaingest with per-source breakdowns. SPF, DKIM, and DMARC checked and graded A through F. Google Postmaster Tools pulled directly into per-domain views. Blocklist monitoring and seed-list inbox-placement testing on the domains you actually send from. One place to answer “why did that campaign underperform,” instead of four browser tabs.

DMARC monitoring

Aggregate rua ingest with per-source and per-IP breakdowns.

Learn more

Auth check

SPF, DKIM, DMARC — parsed, validated, graded A through F.

Learn more

Postmaster Tools

Google reputation, spam rate, delivery errors — per domain.

Learn more

Blocklists + seeds

Continuous blocklist watch. Seed-list inbox placement on demand.

Learn more

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 Parser docs →

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"
}

Observability

Every recipient. Every provider tried. Every reason blocked.

Activity splits into seven filtered inboxes — All, Delivered, Deferred, Bounced, Complained, Suppressed and Blocklisted, and Events. Row-level sparklines, period comparison against yesterday, last week, and last month, saved views, a column picker, keyboard shortcuts (/ r s ?), and anonymous read-only share links for anyone you need to hand a route log to.

Integration

Point your existing code at `smtp.sendrules.net`.

Standard SMTP submission on 587 with STARTTLS or 465 with implicit TLS. Real Let’s Encrypt certificate. No SDK required — your existing SMTP client works today.

import nodemailer from "nodemailer";

const t = nodemailer.createTransport({
  host: "smtp.sendrules.net",
  port: 587,
  secure: false,          // STARTTLS
  auth: {
    user: process.env.SR_USER,
    pass: process.env.SR_PASS,
  },
});

await t.sendMail({
  from: "[email protected]",
  to: "[email protected]",
  subject: "Hello from sendrules",
  text: "Routed through your provider fleet.",
});

Pricing

Public pricing. Real per-1k rates. All the way up.

Sandbox is free. Route from £15/mo annually for 100,000 emails. Fleet from £63/mo annually for 500,000. Command from £199/mo annually for 2M. Enterprise publishes a per-1k rate in your contract instead of “contact for pricing.”

See full pricing

Start sending in under ten minutes.

Start free Book a demo

Sending isn’t a provider problem. It’s a routing problem.

Bring the providers you already trust. We don’t resell sending.

Verify recipients before the send, not after the bounce.

Executed in-band; no pre-flight API call to remember

Per-check block reasons written to the recipient's route log

Rejected recipients do not count against monthly volume

Six routing strategies, one endpoint.

Deliverability tooling, alongside the sending it belongs to.

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 recipient. Every provider tried. Every reason blocked.

import nodemailer from "nodemailer"; const t = nodemailer.createTransport({ host: "smtp.sendrules.net", port: 587, secure: false, // STARTTLS auth: { user: process.env.SR_USER, pass: process.env.SR_PASS, }, }); await t.sendMail({ from: "[email protected]", to: "[email protected]", subject: "Hello from sendrules", text: "Routed through your provider fleet.", });

One SMTP endpoint. Every provider. Verified before the send. Autoresponders parsed for contacts.

Eight stages between your sendMail() and their inbox.

Your app

SMTP ingress

Quality gate

Grid router

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Your app

SMTP ingress

Quality gate

Grid router

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Sending isn’t a provider problem. It’s a routing problem.

Bring the providers you already trust. We don’t resell sending.

Verify recipients before the send, not after the bounce.

Six routing strategies, one endpoint.

Round-robin, weighted, priority

Sticky-sender

MX-based ISP routing

Route by the recipient’s real mail server.

Deliverability tooling, alongside the sending it belongs to.

DMARC monitoring

Auth check

Postmaster Tools

Blocklists + seeds

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

Every recipient. Every provider tried. Every reason blocked.

Point your existing code at smtp.sendrules.net.

Public pricing. Real per-1k rates. All the way up.

Start sending in under ten minutes.

One SMTP endpoint. Every provider. Verified before the send. Autoresponders parsed for contacts.

Eight stages between your sendMail() and their inbox.

Your app

SMTP ingress

Quality gate

Grid router

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Your app

SMTP ingress

Quality gate

Grid router

Provider fleet

Recipient MX

Autoresponder parser

Signals & control

Sending isn’t a provider problem. It’s a routing problem.

Bring the providers you already trust. We don’t resell sending.

Verify recipients before the send, not after the bounce.

Six routing strategies, one endpoint.

Round-robin, weighted, priority

Sticky-sender

MX-based ISP routing

Route by the recipient’s real mail server.

Deliverability tooling, alongside the sending it belongs to.

DMARC monitoring

Auth check

Postmaster Tools

Blocklists + seeds

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

Every recipient. Every provider tried. Every reason blocked.

Point your existing code at smtp.sendrules.net.

Public pricing. Real per-1k rates. All the way up.

Start sending in under ten minutes.

One SMTP endpoint.
Every provider.
Verified before the send.
Autoresponders parsed for contacts.

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

Point your existing code at `smtp.sendrules.net`.

One SMTP endpoint.
Every provider.
Verified before the send.
Autoresponders parsed for contacts.

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

Point your existing code at `smtp.sendrules.net`.