About This Launch
uChecker runs a raw mailing list and returns Good, Bad and Risk with the 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.
Why I Built This
We kept getting vague valid or invalid verdicts from other checkers with no evidence, so we built a checker that keeps the full SMTP reply for every address and never counts Unknown as valid.
Launch Details
CategorySaaS
StageLive
ListedAugust 16, 2026