zimbra.com

Delegation · The nameservers at the parent and in the zone should be the same. Only at the parent: dns1.p03.nsone.net, dns2.p03.nsone.net, dns3.p03.nsone.net, dns4.p03.nsone.net; only in the zone: dns1.p05.nsone.net, dns2.p05.nsone.net, dns3.p05.nsone.net, dns4.p05.nsone.net. dns1.p03.nsone.net, dns1.p05.nsone.net, dns2.p03.nsone.net, dns2.p05.nsone.net, dns3.p03.nsone.net, dns3.p05.nsone.net, dns4.p03.nsone.net, dns4.p05.nsone.net report NS dns1.p05.nsone.net dns2.p05.nsone.net dns3.p05.nsone.net dns4.p05.nsone.net.

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.

SPF · The ptr mechanism in SPF records is deprecated due to performance issues and should be avoided.

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: us-smtp-inbound-1.mimecast.com, us-smtp-inbound-2.mimecast.com

DMARC · DMARC subdomain policy is sp=none, so spoofed mail from subdomains is not blocked. Consider sp=quarantine or sp=reject.

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.