What is "xmail"

XMail is a free open-source, POP3/ ESMTP mail server for Unix and Microsoft Windows operating systems, developed by Davide Libenzi. Unlike other email servers, XMail does not require that each user have a system account, instead it uses flat-file databases to store user information. XMail is a light-weight email server ideally suited for use in situations where other servers such as sendmail and qmail would be overkill.