uChecker is a bulk email checker for messy lists. Drop a .txt or .csv, one job can take up to 9 million addresses at about 3200 a minute. Results come back as Good, Bad and Risk. Anything that cannot be checked goes to Unknown, never counted as valid. The full mail-server reply is stored, so a deleted mailbox, a frozen account and an over-quota box stay three different outcomes. Dashboard app.uchecker.net, API api.uchecker.net/docs, Telegram @uchecker_bot, MCP uchecker.net/mcp.