Another possibility (somewhat cleaner from an OOPy perspective :) would be to define accessors that return a reference to the hash:

sub new {
  my $class = shift;
  $class = ref $class || $class;

  my $self = {};
  $self->{_smtp} = {};

  bless $self, $class;
}

sub smtp {
  my $self = shift;
  return $self->{_smtp}
}
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Then you can use $node->smtp->{status} or what not to access items. You can even get fancy and let the accessor return slices and what not. C.f. also the Class::MethodMaker module which will write this kind of thing for you.