I think it would be better to separate this condition, thoughts?

```ruby
<% if !node['postfix']['virtual_domains'].empty? -%>
virtual_alias_domains = <%= node['postfix']['virtual_domains'].join(' ') %>
<% end -%>

<% if !node['postfix']['virtual_aliases'].empty? -%>
virtual_alias_maps = hash:/etc/postfix/virtual
<% end -%>
```