DFY GTM Systems

Free Lead List Checker Score Your B2B Lead List

Paste your lead list (one email per line, or CSV) and get an instant quality report. The checker flags invalid syntax, duplicates, disposable free-mail domains, and role-based addresses like info@ that kill reply rates then scores the list out of 100.

How this check works

  1. 01

    Every line is parsed as an email or CSV row and checked against the RFC-style email syntax pattern.

  2. 02

    Duplicates are detected after lowercasing and trimming, the same way sending tools dedupe.

  3. 03

    Addresses are compared against 40+ free mailbox providers (Gmail, Yahoo, Outlook…) and common role prefixes (info@, sales@, support@…).

  4. 04

    The final score weighs valid syntax, uniqueness, and the share of business-domain addresses.

How to fix common problems

High duplicate rate

Dedupe before upload most sending tools charge per contact and will happily email the same person twice from different campaigns, which reads as spam behavior.

Too many role accounts

info@ and sales@ addresses rarely reply and bounce more often. Enrich the record to find a named person, or drop the row.

Free-mail heavy list

A B2B list dominated by gmail.com addresses usually means weak targeting. Rebuild the list from company domains instead of personal inboxes.

Example

A 1,000-row list with 940 valid syntax, 40 duplicates, and 60 role/free addresses scores ~84/100 shippable, but removing the 100 weak rows protects sender reputation.

FAQ

Does this tool verify that emails actually exist?
No. This checks syntax, duplicates, and address quality. For mailbox-level verification, use the Email List Validator, which checks each domain's MX records.
Is my lead list uploaded anywhere?
No. Everything runs in your browser. The list never leaves your device.
What is a good lead list score?
85+ is campaign-ready. 70–85 needs cleaning first. Below 70, rebuild or re-enrich the list before sending anything.

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