additional_source_selection_rates

Since: Dev Builds Only

The functionality described in this section requires a dev build of KumoMTA. You can obtain a dev build by following the instructions in the Installation section.

Specifies additional source selection constraints that cut across the per-site-per-source scoping of the source_selection_rate option.

This option can be used to help manage IP-warmup. Please read the source_selection_rate documentation to understand how source selection rate limiting functions.

The value of this option is a map from the rate limit name to the desired rate limit, and allows you to express multiple constraints.

For example, you could implement a overall selection limit, independent of the destination site, for a given named source like this:

kumo.on('get_egress_path_config', function(domain, source_name, site_name)
  return kumo.make_egress_path {
    additional_source_selection_rates = {
      [string.format('overall-source-limit-%s', source_name)] = '10,000/day,max_burst=1',
    },
  }
end)

Note

If you are using the shaping helper, it will automatically populate entries in this map when you specify provider_source_selection_rate in a provider block in your shaping.toml and will cause that limit to apply to that source across all sites that map to that provider:

[provider."Office 365".sources."new-source"]
provider_source_selection_rate = "500/d,max_burst=1"