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

kumo.dns.set_mx_negative_cache_ttl(DURATION)

{{since('2025.03.19-1d3f1f67')}}

Set the negative cache TTL that should be used when caching an MX resolution failure.

DURATION is either a number expressed as optionally fractional seconds, or a human readable duration string like "5s" to specify the units.

The default value for this is "5 minutes".

kumo.on('pre_init', function()
  kumo.dns.set_mx_negative_cache_ttl '10m'
end)