Xmail是Internet和Intranet邮件服务器具有一个SMTP服务器，POP3服务…

代码说明：

XMail is an Internet and intranet mail server featuring an SMTP server, POP3 server, finger server, multiple domains, no need for users to have a real system account, SMTP relay checking, RBL/RSS/ORBS/DUL and custom ( IP based and address based ) spam protection, SMTP authentication ( PLAIN LOGIN CRAM-MD5 POP3-before-SMTP and custom ), a POP3 account syncronizer with external POP3 accounts, account aliases, domain aliases, custom mail processing, direct mail files delivery, custom mail filters, mailing lists, remote administration, custom mail exchangers, logging, and multi-platform code. XMail sources compile under GNU/Linux, FreeBSD, OpenBSD, NetBSD, OSX, Solaris and NT/2K/XP.