Open-Source Python Tool Lets Marketers Bulk-Verify Email Lists Before Campaigns

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A developer has released mailvalid-bulk-verify, a free, open-source Python command-line tool designed to validate email lists before marketing campaigns are sent. The tool checks each address for syntax errors, MX records, SMTP-level mailbox existence, disposable domains, catch-all configurations, and role-based addresses. Users can run it with a single command against a CSV file, and it returns an annotated version of the same file with validity status, confidence scores, and flag columns for each address. The project uses the MailValid API, which offers 100 free credits at registration with no credit card required, and charges $0.001 per email beyond that. The tool is publicly available on GitHub, and its author argues it addresses a core deliverability problem, since B2B email data decays at roughly 2% per month and high bounce rates can trigger spam filters for an entire sending domain.

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