poplimitd is a daemon process that monitors a server maillog file for POP3 or IMAP connections. Using configurable settings it monitors the rate of logins based on the 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. On servers that suffer from high POP3/IMAP load, this can dramatically modify user behaviour and limit POP and IMAP connections and load.
mysqmail-qmail-pop3d is a replacement for the qmail standard checkpasswd that does authentication via a MySQL table. When done, it sets up two more environment variables, MYSQMAIL_USERNAME and MYSQMAIL_DOMAINNAME. The mysqmail qmail-pop3d replacement will use these variables to do the traffic accounting in the MySQL table for the account.
stdnoj is a cross-platform C++ class library that includes classes for using portable strings, databases, SMTP, POP, NNTP, arrays, files, directories, logging, email, and sockets. While templates are used, no reliance upon STL or other (traditionally error-prone) technologies has been used, which increases portability between compilers.