20M+ rows processed
Know the inbox behind every contact
Enrich any email list from CSV or Excel with ESP provider, category, and MX records—pulled live from DNS. No paywall. Up to 50,000 rows per file.
Built for ops and revenue teams who need reliable routing signals, not guessed labels.
We built this because we needed reliable ESP data for client outbound campaigns — and every existing tool either charged per record or guessed wrong. So we made it free.
Import CSV or Excel or drag here
Include an email column · .csv, .xlsx, .xls · Max 32 MB
Quick lookup
One email or domain—no file needed. Same live MX and ESP detection as bulk upload.
How it works
Three steps from raw spreadsheet to enriched export
Upload
CSV or Excel with an email column. Other columns are preserved in the export.
Resolve
We dedupe domains and query MX in parallel—no AI, no fabricated providers.
Export
Download enriched CSV with provider, category, MX hostnames, and priorities.
Built by IntentSignal
MX Checker is built by IntentSignal. We build your complete TAM, enrich it with fields you can't get anywhere else, and run outbound campaigns that have driven 90+ opportunities in 2 months for companies like Gainsight, Upside, and Route.