use warnings;
use strict;

my $match = <<'EOF';
dddd@fgg.com
cccc@fgg.com
eeee@fgg.com
dddd@fgg.com

EOF

my %seen;
my @r;

foreach my $v ( split /\n/, $match ) {
    unless ( $seen{$v}++ ) {
        push @r, $v;
    }
}
$" = "\n";
print "@r";