uChecker

About

uChecker takes a raw list and returns Good, Bad and Risk with the full SMTP reply kept. Upload .txt or .csv, up to 9 million addresses in one job, about 3200 a minute, no pre-clean. Unknown is never counted valid. Use app.uchecker.net, api.uchecker.net/docs, @uchecker_bot, or https://uchecker.net/mcp. Thirteen DNS tools stay free at https://uchecker.net/tools.