MX resolving to A and AAAA skipped

KumoMTA Configuration
1

Hi,

A customer of ours is trying to send an email to a domain that has an MX which points to a hostname with both an A and AAAA record. However, we are still seeing `MX consisted solely of hosts on the skip_hosts list`.

It points to a Strato SMTP server and upon checking we are able to resolve it to the IPv4 and IPv6 addresses via our Unbound resolver.

We have our skip_hosts set to `skip_hosts = [“::/0”]`.

Since resolving seems to be fine, I am a bit clueless on the mechanics of skip_hosts and if it indeed still falls back to the A record that shouldn’t be skipped (do not think it does).

Thanks!

2

What scope is your skip_hosts set at?

3

It’s part of the defaults:

['default']
connection_limit = 10
max_connection_rate = "300/min"
max_deliveries_per_connection = 20
max_message_rate = "100/s"
idle_timeout = "60s"
enable_tls = "OpportunisticInsecure"
skip_hosts = ["::/0"]
remember_broken_tls = "3 days"
opportunistic_tls_reconnect_on_failed_handshake = true
consecutive_connection_failures_before_delay = 10
try_next_host_on_transport_error = true
4

It should skip it’s way to the A record. What are you seeing in the logs that imply it may not be?

5

This new commit may help:

new: ip_lookup_strategy option in make_egress_path · KumoCorp/kumomta@654f9b8 · GitHub

6

Will test this one, sounds great!