courier-mta 0.59.0-3ubuntu1~hardy1 (amd64 binary) in ubuntu hardy

 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. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list
 services within a single, consistent, framework.
 .
 This package provides an ESMTP daemon which uses the Maildir format as native storage
 format, supports IPv6, implements SMTP extensions for mailing list
 management and features integrated mail filtering. It can function as an
 intermediate mail relay, relaying mail between an internal LAN and the
 Internet, or perform final delivery to mailboxes.