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 standards 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 behavior 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 recognize 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.