Smail-3 is a

mail transfer agent The mail or post is a system for physically transporting postcards, letters, and parcels. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal syst ...

(MTA) used on

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating systems. It is

Free Software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...

and is licensed under the

GNU GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general us ...

. It aims to be a general and flexible mailer with extensive facilities for checking incoming

e-mail Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email was thus conceived as the electronic ( digital) version of, or counterpart to, mail, at a time when "mail" meant ...

and for routing between disparate networks. It is still in use on the

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...

, but it has been mostly superseded by

Exim Exim is a mail transfer agent (MTA) used on Unix-like operating systems. Exim is free software distributed under the terms of the GNU General Public License, and it aims to be a general and flexible mailer with extensive facilities for checking ...

(which was originally based on Smail) and other more modern

s. Smail-3 still follows a monolithic design model where a single binary controls the core facilities of the MTA. This type of monolithic design is generally considered to be inherently less secure, largely because the whole program normally runs with full system privileges at all times. Nevertheless, Smail's security record has been fairly clean, and has only been the subject of one

BUGTRAQ Bugtraq was an electronic mailing list dedicated to issues about computer security. On-topic issues are new discussions about vulnerabilities, vendor security-related announcements, methods of exploitation, and how to fix them. It was a high-volume ...

advisory. It was designed with security as a primary goal and makes use of several key safe coding practices to avoid some of the most common pitfalls of similar large programs written in C.Weird.com
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References

External links

{{Portal, Free and open-source software

Smail-3 Internet Mailer Message transfer agents Free email server software Free email software Cross-platform software