Show Dev: A sub-25ms edge API to stop cold emails from landing in spam

Erik — Mon, 07 Sep 2026 19:16:22 +0000

Hey everyone! Showcasing a new API to solve a real-world problem for cold email outreach: DomainSignal.io.

The Problem I Set Out to Solve

In B2B cold outbound, cross-provider sending is a silent killer.

When newly provisioned Google Workspace mailboxes blast enterprise Microsoft 365 inboxes, Microsoft’s Exchange Online Protection (EOP) flags the traffic as untrusted external outreach. Quarantine rates spike, open rates crash from 40% to under 10%, and secondary sending domains burn out in weeks.

On top of that, enterprise gateways like Proofpoint automatically detonate click-tracking links, flagging entire sending domains as malicious.

Legacy data platforms (Apollo, ZoomInfo) try to solve this with web scrapers that look for historical HTML tags or old job postings, but they're slow (800ms–2s), often months out of date, and cost $0.05+ per lookup.

What I Built

We built a low-latency edge engine deployed globally across 300+ edge locations that inspects corporate cloud identity and mailbox infrastructure directly at the network layer in under 25ms.

Instead of scraping website HTML, it runs fast concurrent network probes to determine the true ground-truth infrastructure of any target company.

What the API Returns:

json
{
  "domain": "stripe.com",
  "mailbox_infrastructure": {
    "primary_provider": "Google_Workspace",
    "matching_send_recommendation": "Send via Google Mailbox"
  },
  "tenant_profile": {
    "is_active_enterprise": true,
    "sso_vendor": "Okta"
  },
  "outbound_guidance": {
    "link_safety": "High Risk: Strip Hyperlinks (Proofpoint Active)"
  },
  "security_posture": {
    "dmarc_present": true,
    "dmarc_policy": "reject"
  }
}

and more

How Outbound Teams Use It

Provider-Matched Routing: Automated sequencers (Instantly, Smartlead) split lead lists before sending, routing Google-to-Google and Outlook-to-M365 to keep sender reputation intact.

Proofpoint Link-Stripping: If an Email Security Gateway is detected, pipelines automatically strip tracking pixels and links to avoid sandbox detonation.

Dead Lead Quarantine: If DMARC is missing or the domain has no operational mail server, the lead is quarantined before wasting sender reputation.

Looking for Feedback!

👉 DomainSignal.io

You can test any company domain right on the homepage without signing up.

Would love brutal feedback from anyone in the API, sales-tech, or SaaS space: