kumomta/docs/reference/kumo.dns/configure_unbound_resolver.md

kumo.dns.configure_resolver{PARAMS}

{{since('2023.11.28-b5252a41')}}

By default, KumoMTA will parse the system resolver configuration and use that to drive its internal caching Hickory DNS resolver.

This function allows you to configure DNS resolving differently from your system configuration, and to use Unbound embedded DNS resolver.

If you have enabled DANE for output SMTP then you must enable the unbound resolver in order to be able to process DNSSEC correctly.

!!! note This function should be called only from inside your init event handler.

The parameters to this functions are the same as those to kumo.dns.configure_resolver.

kumo.on('init', function()
  kumo.dns.configure_unbound_resolver {
    options = {
      -- Enable DNSSEC
      validate = true,
    },
    -- By default, if you omit `name_servers`, unbound will
    -- resolve via the root resolvers.
    -- We strongly recommend deploying local caching nameservers
    -- and referencing them here:
    -- name_servers = { '1.1.1.1:53' },
  }
end)