afu-kiel.de

SOA · retry 20m should be shorter than refresh 20m; expire 1h is shorter than 7d; secondaries stop answering too soon when the primary is down. Current values: refresh 20m, retry 20m, expire 1h, negative TTL 10m.

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.

DMARC · DMARC policy is set to 'quarantine'. Consider upgrading to 'reject' for stronger protection once you've verified legitimate emails are passing authentication.

DKIM · The _domainkey name exists but no DKIM key was found under the common selectors. Selectors are provider-specific; check yours with -selector.

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

MX · The following MX hosts could not be resolved to IPv6 addresses: mx1.kserver.org, mx2.kserver.org, mx3.kserver.org

DMARC · DMARC record has no rua tag, so you receive no aggregate reports about who sends mail as your domain. Add rua=mailto:...

MX · These MX addresses have no PTR record, which many receivers treat as a spam signal: 213.178.78.250 (mx3.kserver.org). Ask your hosting provider to set one.

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.