High-Volume Email Verifier Development
Publicada el 2026-07-27
Descripción de la oferta
Python / Node.js Developer for High-Volume Bulk Email & Webmail Verifier (MX Lookup + SMTP Handshake) I need a robust bulk-email verifier that can chew through hundreds of thousands of addresses per run without falling over. The core routine must combine fast DNS MX lookups with an actual SMTP handshake so every result is as close to “definitive” as possible, even for web-mail giants such as Gmail, Outlook, Yahoo and the usual corporate servers. We are looking for an experienced backend developer to build a custom, high-speed, and accurate bulk email verification tool/script. The system must validate large lists of webmail and domain addresses (Gmail, Outlook/Hotmail, Yahoo, custom domains) without sending actual emails. Key Requirements & Verification Workflow: 1. Syntax & Domain Validation: - Perform strict RFC 5322 syntax and regex formatting checks. - Detect disposable/temporary email domains and role-based addresses (admin@, info@, support@). 2. MX Record & DNS Verification: - Direct DNS lookups to verify domain MX (Mail Exchange) records. - Rank and route checks to primary and fallback mail servers. 3. SMTP Handshake Verification: - Establish live socket connections on Port 25 / 587. - Execute standard SMTP commands (HELO/EHLO -> MAIL FROM -> RCPT TO) to ping the destination server. - Accurately parse response codes (e.g., 250 OK vs. 550 User Unknown / hard bounce). - Gracefully handle connection timeouts, tarpitting, and greylisting. 4. Advanced Webmail & Catch-All Detection: - Detect "Catch-All" (accept-all) server configurations to prevent false positives. - Handle webmail providers (Gmail, Microsoft 365, Yahoo, AOL) with specialized handling/API/headers where standard SMTP handshakes are restricted or rate-limited. 5. Performance, Scale & IP Management: - Multi-threading / Async execution for bulk validation (processing thousands of emails efficiently). - Rotating proxy support (HTTP/SOCKS5) to bypass rate limits, greylisting, and IP blacklisting. Have to deal with Bulk Email database, approx 4Lacs Emails (Gmail/ Yahoo/ Outlook & Custom domain Webmails) Deliverables: - Source code (Python or Node.js preferred) with clean documentation. - Input: Accepts CSV/TXT files with raw email lists. - Output: Export results to CSV/JSON with clear classifications (Valid, Invalid, Catch-All, Risky/Disposable, Unknown) alongside error response reason codes. - Brief setup guide to run locally or deploy on a VPS. To Apply: 1. Please mention your experience with SMTP sockets, DNS resolving, or anti-spam protocols. 2. Include the secret word "VALIDATE" at the top of your proposal so I know you read the full description. Budget can be finalised once we discus. TQ
Skills
Fuente original: freelancer