Solution Review: Extract Email Addresses

# Assume that $file is already defined and it contains the name of the file
open my $fh, '<', $file;

my $username = qr/\w+/;
my $domain = qr/\w+/;
my $top_level = qr/\w{2,3}/;
my $country = qr/[a-z]{2,3}/;
my $email = qr/$username\@$domain\.$top_level(\.$country)?/;

while(<$fh>) {
  say "$1" while $_ =~ /($email)/ig;
}