set_mx_concurrency_limit

kumo.dns.set_mx_concurrency_limit(LIMIT)

Since: Version 2025.05.06-b29689af

The functionality described in this section requires version 2025.05.06-b29689af of KumoMTA, or a more recent version.

Set the maximum number of concurrent MX lookups that we will allow to send to the upstream DNS resolver.

The default is 128.

In earlier versions of kumomta, there was no default, issuing as many queries as we were requested to make at any given moment.

kumo.on('pre_init', function()
  kumo.dns.set_mx_concurrency_limit(128)
end)