The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP, SSL, and HTTP.

• 快递邮件的传输代理（MTA）是一个集成的邮件/群件服务器基于开放商品协议，如ESMTP的IMAP，POP3，LDAP的，SSL等，和HTTP。