There is a CPAN module that will match email addresses inside a string; Email::Find. Here's an example using this module:

#!/usr/bin/perl -w

use strict;
use Email::Find qw(find_emails);

use vars qw(@MATCHES);

my $text = 'user@somewhere.com not an email address me@home.com';

find_emails($text, \&callback);

print join "\n", @MATCHES;

sub callback {
  my $email    = shift;
  my $original = shift;

  push @MATCHES, $email->format;
  return $original;
}
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Warning: the find_emails() routine will modify the original text. Make sure that you always return the original email text (as shown above), so that your input text does not mysteriously change.