Why native MX matching still cross-sends
Instantly can inspect MX and bucket a lead as Google, Microsoft, or “Other.” That works until the receiving domain sits behind Proofpoint, Mimecast, or another security gateway. The public MX no longer looks like Microsoft or Google—so the sequencer classifies the lead as Other and falls back to whatever inbox is next in the rotation.
That fallback is blind routing: a warmed Google seat into an M365 tenant (or a tracked link into a sandbox). DomainSignal does not replace Instantly. It queries Microsoft Entra ID and Google discovery at the edge to reveal the underlying tenant even when MX is a gateway. Instantly still sends. DomainSignal decides which Instantly campaign—and which sending pool—gets the lead.
What Instantly sees
Proofpoint / Mimecast MX → “Other” → next mailbox in the rotation.
What DomainSignal sees
Entra ID tenant + Google discovery behind the gateway, in ~18ms.
How you send
Google→Google, Outlook→M365, gateway leads as plain text only.
Realistic Instantly vs Instantly + DomainSignal
Same sequencer. Same warmup. The difference is pre-flight matching before you upload the campaign.
| Metric | Standard Instantly (Blind Routing) | Instantly + DomainSignal (Pre-Flight Matched) | The Realistic Delta |
|---|---|---|---|
| Primary Inbox Placement | 50% – 60% | 75% – 85% | +25% to +30% lift |
| Sustained Open Rate | 12% – 18% | 28% – 38% | ~2x higher opens |
| Sending Mailbox Lifespan | 3 to 6 weeks | 5 to 8+ months | 4x to 5x longer life |
| Monthly Domain Overhead | ~$1,250/mo | ~$300/mo | Saves ~$950/month net |
Transparency Note
Open tracking is disabled on plain-text gateway leads on purpose. Proofpoint and Mimecast sandboxes click every tracked link and fire every pixel before a human sees the thread. Those detonations blacklist sending domains and inflate fake opens. DomainSignal flags gateway tenants so you strip tracking and send plain text. You lose pixel-based open rates on that cohort; you keep the mailbox. Treat replies and meetings as the KPI—not sequencer “opens.”
Pre-flight a CSV, then upload to Instantly
Three steps. No Instantly replacement, no new sequencer.
Step 1
Enrich the list
Upload your Instantly-ready CSV to the Domain CSV Enricher. DomainSignal probes each domain at the edge and labels Google Workspace, Microsoft 365, and enterprise gateways.
Step 2
Download three cohorts
Export Google leads, Outlook / M365 leads, and gateway leads as separate CSVs. Gateway rows are the ones that Instantly would have dumped into “Other.”
Step 3
Map campaigns in Instantly
Upload Google CSV to Google sending accounts, M365 CSV to Outlook accounts, and gateway CSV to a plain-text sequence with tracking off. Instantly rotates inboxes inside the right trust boundary.