FlexPOP is a new POP server developed by VA Linux, which has the merit of being fast and secure. FlexPOP supports the Maildir format, thus it can be used on large-scale systems which use NFS spools. Other strong points include user authentication with LDAP, POP before SMTP support, POP lock (mutual exclusion) support when accessed concurrently, timeout setting support for POP commands, delayed response support when POP authentication errors occurred, and so on.