Just for the fun of it - sendmail has this:

# if defined(__linux__) && MAXHOSTNAMELEN < 255
   /*
   **  override Linux weirdness: a FQHN can be 255 chars long
   **  SUSv3 requires HOST_NAME_MAX ("Maximum length of a host
   **  name (not including the terminating null) as returned from the
   **  gethostname() function.") to be at least 255.  c.f.:
   **  http://www.opengroup.org/onlinepubs/009695399
   **  but Linux defines that to 64 too.
   */
#  undef MAXHOSTNAMELEN
#  define MAXHOSTNAMELEN	256
# endif /* defined(__linux__) && MAXHOSTNAMELEN < 255 */

-- 
Please don't Cc: me, use only the list for replies.