sendrules
Product
  • Overview
    How sendrules fits between your app and every provider.
  • SMTP Proxy
    One endpoint. Every provider you already trust.
  • Grids
    Six routing strategies. Coverage warnings. Failover.
  • Quality Gate
    Verify recipients before the send, not after the bounce.
  • ISP Routing
    Route by the recipient's live MX record — not domain strings.
  • Ramp-up
    Auto-advancing cap with bounce/complaint safety gates.
  • Limits & Queue
    Four-tier caps. Queue, don't drop. Midnight-UTC release.
  • Webhooks
    HMAC-signed. Retried on schedule. Replayable.
  • Activity
    Seven filtered inboxes. Sparklines. Share links.
  • Inbound
    Receive + classify replies, bounces, and OOOs.
  • Autoresponder Parser
    Harvest contacts from OOO replies into lists — webhook or CSV.
Deliverability
  • Overview
    The suite most vendors sell separately.
  • DMARC Monitoring
    rua ingest with per-source breakdowns.
  • Auth Check
    SPF / DKIM / DMARC, graded A through F.
  • Postmaster Tools
    Google Postmaster data in per-domain views.
  • Blocklists
    Continuous blocklist + seed-list inbox placement.
PricingDocsCustomers
Sign inStart free

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 freeSee a live route log
sendrules · pipeline
how it works
01
Your appany SMTP client
NodePythonRubyGo
02
SMTP ingresssmtp.sendrules.net
587 STARTTLS465 implicitIP allow-list
03
Quality gate6 checks
SyntaxSuppressionDisposableRoleTypoReacher
04
Grid router6 strategies
RRWeightedPriorityStickyMX-ISP+ ramp-up
05
Provider fleet15 providers
SESSendGridPostmarkMailgun+11
06
Recipient inboxdelivery + replies
GmailYahooOutlookAppleOther
07
Autoresponder parserOOO → contacts
HarvestRegex fieldsIgnoreWebhookCSV
08
Signals & controlobservability
DMARCPostmasterBlocklistsHMAC webhooksActivity
15
providers supported end-to-end
6
routing strategies, one endpoint
4
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.

01

Your app

Any SMTP client, any framework.

Node · Python · Ruby · Go · PHP · curl
02

SMTP ingress

smtp.sendrules.net, 587 STARTTLS + 465 implicit.

AUTH LOGIN/PLAINIP allow-listReal LE cert
03

Quality gate

Every recipient scored in the DATA phase.

SyntaxSuppressionDisposableRoleTypoReacher
04

Grid router

Pick a strategy. Fail over automatically.

RRWeightedPriorityRandomStickyMX-ISP
05

Provider fleet

Your accounts. Your reputation. Your quota.

SESSendGridPostmarkMailgun+11 more
via the provider that best fits the recipient's ISP
06

Recipient MX

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

DeliveryBounceComplaintReplyOOO
07

Autoresponder parser

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

Harvest emailsRegex fieldsIgnore listWebhookCSV export
08

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
  1. Your app

    01

    Any SMTP client, any framework.

    Node · Python · Ruby · Go · PHP · curl
  2. SMTP ingress

    02

    smtp.sendrules.net, 587 STARTTLS + 465 implicit.

    AUTH LOGIN/PLAINIP allow-listReal LE cert
  3. Quality gate

    03

    Every recipient scored in the DATA phase.

    SyntaxSuppressionDisposableRoleTypoReacher
  4. Grid router

    04

    Pick a strategy. Fail over automatically.

    RRWeightedPriorityRandomStickyMX-ISP
  5. Provider fleet

    05

    Your accounts. Your reputation. Your quota.

    SESSendGridPostmarkMailgun+11 more
  6. Recipient MX

    06

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

    DeliveryBounceComplaintReplyOOO
  7. Autoresponder parser

    07

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

    Harvest emailsRegex fieldsIgnore listWebhookCSV export
  8. 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 productParser 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
  • [email protected]procurement
  • [email protected]legal
  • [email protected]on leave
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 freeBook a demo
sendrules

One SMTP endpoint across 15 providers. Verify recipients before the send, route by real MX, and monitor DMARC in the same product.

Sign inStart free

Product

  • SMTP Proxy
  • Grids
  • Quality Gate
  • ISP Routing
  • Ramp-up
  • Limits & Queue
  • Webhooks
  • Activity
  • Inbound
  • Autoresponder Parser
  • Integrations
  • Changelog

Deliverability

  • DMARC Monitoring
  • Auth Check
  • Postmaster Tools
  • Blocklists
  • Free Tools
  • Providers

Company

  • Customers
  • Pricing
  • Contact
  • About
  • Status
  • Security

Legal

  • Terms
  • Privacy
  • DPA
  • Acceptable Use

sendrules.com — marketing. Sending infrastructure operates separately at smtp.sendrules.net. © 2026 sendrules.com

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