Something that has to be done to break a network program (typically a mailer) on a non- Unix system so that it will interoperate with Unix systems. The hack may qualify as "Unix brain damage" if the program conforms to published standard s and the Unix program in question does not. Unix brain damage happens because it is much easier for other (minority) systems to change their ways to match non-conforming behaviour than it is to change all the hundreds of thousands of Unix systems out there.
An example of Unix brain damage is a kluge in a mail server to recognise bare line feed (the Unix newline) as an equivalent form to the Internet standard newline, which is a carriage return followed by a line feed. Such things can make even a hardened jock weep.
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