smtp2go.com

Delegation · The nameservers at the parent and in the zone should be the same. Only at the parent: sns1.treshna.co.nz, sns2.treshna.co.nz; only in the zone: ns4.smtpcorp.com, sns4.treshna.co.nz. ns2.smtpcorp.com, ns4.smtpcorp.com, sns1.treshna.co.nz, sns2.treshna.co.nz, sns3.treshna.co.nz, sns4.treshna.co.nz report NS ns2.smtpcorp.com ns4.smtpcorp.com sns3.treshna.co.nz sns4.treshna.co.nz.

Delegation · The addresses at the parent (glue) differ from the addresses in the zone: ns2.smtpcorp.com (glue 207.58.142.213, zone 185.3.94.65). Update the glue at your registrar.

Delegation · None of the nameservers has an IPv6 address, so IPv6-only resolvers can't reach them.

Nameservers · These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns2.smtpcorp.com: "9.18.49-1~deb12u2-Debian"; ns4.smtpcorp.com: "9.18.44-1~deb12u1-Debian"; sns1.treshna.co.nz: "9.20.29-1~deb13u1-Debian"; sns2.treshna.co.nz: "9.18.49-1~deb12u2-Debian"; sns3.treshna.co.nz: "9.18.44-1~deb12u1-Debian"; sns4.treshna.co.nz: "9.20.29-1~deb13u1-Debian". Hide or replace the version string.

DNSSEC · The zone is not signed with DNSSEC, so answers can be spoofed. Enable DNSSEC at your DNS provider and publish the DS record at your registrar.

DNSSEC · DNSSEC is not enabled for this domain. Consider enabling DNSSEC to protect against DNS spoofing attacks.

DKIM · 1024-bit RSA keys are the minimum and are considered weak today: s2 (1024 bits). Rotate to a 2048-bit key.

TLS · MTA-STS is not configured, so other mail servers fall back to unencrypted delivery when TLS fails or is stripped by an attacker. Publish a _mta-sts TXT record and a policy at https://mta-sts.<domain>/.well-known/mta-sts.txt.