MeTA1 is a modularized message transfer agent consisting of five (or more) persistent processes, four of which are multi-threaded.MeTA1 consists of five main modules of which only one runs as root
mcp: the main control program is similar to inetd(8): it starts all other MeTA1 modules and watches over their execution. mcp runs as root in order to bind to port 25 and to change the uid of the processes it starts.
The syntax of the MeTA1 configuration file is very simple and resembles C programs or the BIND 9 configuration files. A configuration file does not require any special layout, e.g., tabs or one option per line, but relies on braces and semicolons as structuring elements.
The first release of MeTA1 is intended to be used as a secure and efficient mail gateway. It offers features that are not available in sendmail 8 (or some other open source MTAs), however, it does not provide any builtin support for mail content modification, e.g., masquerading of addresses or changing (addition, removal) of headers. Those features are currently only available via the pmilter API.