Postal

Postal is an open source, complete and fully featured mail server intended for use by websites and web servers. It provides mail-server software for people and organizations that operate web infrastructure and need their websites or servers to handle email. Postal is specifically described in relation to websites and web servers, rather than as a general-purpose email program for individual users. The available information does not identify a particular paid product that Postal is designed to replace, so it cannot be presented as a direct alternative to a specific commercial email server. One limitation is that the stated facts do not list its individual features or explain how its capabilities differ from those of paid products. “Complete and fully featured” is the only description provided of its scope, so anyone comparing Postal with a commercial mail server will need to consult the project’s documentation for a detailed feature comparison.