my %services = (
    service1 => { email => \@maintainers },
    service2 => { email => \@maintainers },
);

##</code><code>##

my %services = (
    service1 => { email => [ @maintainers ] },
    service2 => { email => [ @maintainers ] },
);

##</code><code>##

#!/usr/bin/env perl
use strict;
use warnings;
use feature 'say';

my $a = "original";

my $a_ref1 = \$a;
my $a_ref2 = \$a;
my $a_copy = $a;

say "\$a is $a";
say "\$a_ref1 is $$a_ref1";
say "\$a_ref2 is $$a_ref2";
say "\$a_copy is $a_copy";

say "OK, let's alter only the first reference (\$a_ref1):";

$$a_ref1 = "altered";

say "\$a is $a";
say "\$a_ref1 is $$a_ref1";
say "\$a_ref2 is $$a_ref2";
say "\$a_copy is $a_copy";

##</code><code>##

$a is original
$a_ref1 is original
$a_ref2 is original
$a_copy is original
OK, let's alter the first reference ($a_ref1):
$a is altered
$a_ref1 is altered
$a_ref2 is altered
$a_copy is original