Who Sends Email From This Domain?
Discover which email service providers (e.g. Google, Amazon SES, SendGrid, Mailchimp) are authorized to send email for any domain, and inspect their inbound mailbox routing.
We inspect public MX, SPF includes, nested delegations, and DKIM selectors. We do not send email.
Why analyzing your sending roster matters.
Clean up vendor sprawl, prevent SPF lookup limit errors, and understand your company's true email sending footprint.
Audit Third-Party ESP Sprawl
Identify forgotten marketing tools, old transactional providers, and legacy CRM vendors still authorized to send from your domain.
Prevent SPF 10-Lookup PermErrors
Every third-party 'include:' eats into your RFC 7208 10-lookup limit. Finding and removing unused providers fixes delivery failures.
Unroll Hidden Nested Includes
Many domains delegate SPF through 'include:spf.acme.com'. Our engine recursively follows up to depth 2 to reveal true underlying ESPs.
Inspect Inbound vs. Outbound Separation
Understand whether a domain runs a unified stack (e.g. Google Workspace) or splits inbox routing from automated sending pipelines.
Identify email senders via API.
Integrate automated vendor discovery and SPF permission mapping into your security audits or customer onboarding flows.
Install the Node.js package
npm install reloop-emailQuery sender permissions with Node.js
1import Reloop from 'reloop-email';2
3const reloop = new Reloop(process.env.RELOOP_API_KEY);4
5const report = await reloop.tools.whoSends({6 domain: 'stripe.com',7});8
9console.log(`Inbox: ${report.inbox.provider}`);10console.log(`Verdict: ${report.verdict}`);11console.log('Authorized Senders:', report.senders.map(s => s.vendor));Inspect JSON sender fingerprint report (200 OK)
1{2 "domain": "stripe.com",3 "resolvedAt": "2026-08-31T12:00:00.000Z",4 "responseTimeMs": 38,5 "verdict": "split_stack",6 "headline": "Google Workspace inbox. Mail is sent via Amazon SES and SendGrid.",7 "summary": "3 providers are authorized to send as stripe.com. Inbound mail routing and outbound delivery operate across separate stacks.",8 "disclaimer": "This is who DNS authorizes, not who sent mail last week. DNS is a permission list, not a volume log.",9 "inbox": {10 "provider": "Google Workspace",11 "exchanges": ["aspmx.l.google.com", "alt1.aspmx.l.google.com"]12 },13 "senders": [14 {15 "vendor": "Google Workspace",16 "role": "inbox_and_send",17 "confidence": "high",18 "leftover": false,19 "evidence": [20 { "type": "spf_include", "value": "_spf.google.com" },21 { "type": "dkim_selector", "value": "google" }22 ]23 },24 {25 "vendor": "Amazon SES",26 "role": "send",27 "confidence": "high",28 "leftover": false,29 "evidence": [30 { "type": "spf_include", "value": "amazonses.com" }31 ]32 }33 ],34 "unnamed": {35 "ip4": [],36 "ip6": [],37 "includes": []38 },39 "spf": {40 "published": true,41 "qualifier": "~all",42 "lookupCount": 2,43 "rawRecord": "v=spf1 include:_spf.google.com include:amazonses.com ~all"44 },45 "nextStep": {46 "title": "Consolidate sending infrastructure with Reloop",47 "body": "Replace multiple sending vendors with Reloop's developer-first SMTP and API platform for 100% inbox placement.",48 "href": "/dashboard/signup"49 },50 "subdomainNote": null51}Frequently asked questions.
Everything you need to know about SPF includes, nested unrolling, DKIM selectors, and inbox/outbound separation.
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