poplimitd is a daemon process that will monitor your server maillog file for POP3 or IMAP connections. Using configurable settings it monitors the rate of logins based on user account and IP address. If it finds excessive usage, it will send a preconfigured email with the users information to that user asking them to stop it. On servers that suffer from high POP3/IMAP load, this can dramatically modify user behavior and limit POP and IMAP connections and load.