Well that will work well for extracting most (non-uucp style) email-like strings, but I would run those results through Email::Valid to make sure it is really valid. Also I would make the regex a little more liberal like /\S@\S/.

If you want you can read RFC822 Standard for the Format of ARPA Internet Text Messages. Which will explain why I say be very liberal (you can throw about any silly character in an email address :) ).

grep

grep> grep clue /home/users/*