schweitzer-online.de

SOA · retry 1h should be shorter than refresh 1h. Current values: refresh 1h, retry 1h, expire 7d, 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.

Records · These records have a TTL below 5m, causing extra queries and slower lookups: MX (1m). Low TTLs are useful just before a planned change. The NS TTL at the parent is 1d and in the zone 10m; resolvers may use either.

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

MX · Only one MX record found. For better email reliability, consider adding at least one backup MX server.

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

DKIM · 1024-bit RSA keys are the minimum and are considered weak today: selector1 (1024 bits), selector2 (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.