Discreet Email Validation Audit

I have a single plain-text file filled with email addresses that need to be cleaned, formatted, and double-checked for mailbox existence. Every address must be verified in a completely silent manner—no test messages, pings, or traceable activity that could alert the recipient. Your job is to run a full diagnostic that confirms each address is able to receive mail, flag anything that fails, and return a neatly formatted file ready for campaign use. While doing so, please document the exact tools, APIs, or in-house scripts you rely on (for example, SMTP handshake checks, MX record look-ups, or Hunter.io-style services) and let me know how long the entire run will take once you receive the list. Deliverables: • Cleaned text file, preserving original order, with a new column indicating Valid / Invalid / Catch-all. • Brief report summarising total counts, common failure reasons, and the toolset used. If you can hit a fast turnaround without compromising discretion, I’d love to get started.

Project ID: 40263587