Noun. 1. achromatic color-a color lacking hue; white or grey or black. achromatic colour. color, coloring, colouring, colour-a visual attribute of things that results from the light they emit or transmit or reflect; a white color is made up of many different wavelengths of light.
A good candidate for a mail host is a system that connects your systems to the outside world or to a parent domain. 1  Become superuser on the mail host system. 2  Verify the host name configuration. 3  Update. Create an entry for the new mail host in the appropriate hosts file.  Change the correct configuration 1  file. Restart and test your mail configuration.
hostname is the name given to the end-point (the machine in question) and will be used to identify it over DNS if that is configured. domain is the name given to the 'network' it will be required to reach the network from an external point (like the Internet)