.output-filter

s|\([0-9]\+\.\)\([0-9]\+\.\)\([0-9]\+\.\)\([0-9]\+\)|xxx.xxx.\3\4|g
s|\([0-9a-zA-Z._-]\+\)\@\([0-9a-zA-Z.-]\+\)\.\([a-zA-Z]\{2,3\}\)|xxx@xxx.\3|g
s|\([0-9a-zA-Z.-]\+\)\.\([a-zA-Z]\{2,3\}\)|xxx.\2|g