nbn-resolving.de

Checked 21 October 2026, 23:31 UTC · via 8.8.8.8
✗Problems found
9 passed 3 warnings 3 failed 3 info

SPF

fail

No SPF record found

Checks

  • ✗
    No SPF record
    No SPF record was found for this domain. SPF is important for preventing email spoofing. Add an SPF record to specify which servers are authorized to send email for your domain.
    #6

DMARC

fail

No DMARC record found

Checks

  • ✗
    No DMARC record
    No DMARC record was found for this domain. DMARC is essential for preventing email spoofing. Add a DMARC record with p=reject or at least p=quarantine.
    #5

DKIM

fail

No keys found under the checked selectors

Found

Selectors
None found
_domainkey
NXDOMAIN

Checks

  • ✗
    No DKIM keys published
    _domainkey.nbn-resolving.de does not exist (NXDOMAIN), so no DKIM keys are published. DKIM helps prevent email spoofing. Configure DKIM with your email service provider.
    #7

DNSSEC

pass

Signed, DS published at parent

Found

DNSKEY records
Yes (2)
DS at parent
Yes
Algorithms
RSASHA256 (8)
Key tags
40810, 41780
Signatures valid until
4 November 2026, 23:27 UTC

Checks

  • ✓ Signed, DS published at parent #8
    DNSSEC is enabled for this domain (DNSKEY and DS present), providing additional security for DNS lookups.
  • ✓ Signatures valid until 2026-11-04 #21
    DNSKEY signatures are valid until 2026-11-04T23:27:15Z.

MX

warn

1 mail server

Found

PriorityHostRecordsReverse DNS
10mail.dnb.deA 193.175.100.144mail.dnb.de ✓

Checks

  • ✓ 1 MX record #9
    Found 1 MX records for this domain.
  • ✓ All hosts resolve #10
    All MX records resolve to valid IP addresses.
  • !
    Hosts without IPv6
    The following MX hosts could not be resolved to IPv6 addresses: mail.dnb.de
    #11
  • !
    Single MX host, no backup
    Only one MX record found. For better email reliability, consider adding at least one backup MX server.
    #12
  • ✓ At most 5 MX records #13
    Found 1 MX records, which is within the recommended range (1-5).
  • ✓ No localhost targets #14
    No MX records pointing to localhost found.
  • ✓ No private IP addresses #15
    No MX records resolving to private IP addresses found.
  • ✓ No CNAME targets #22
    No MX records point to a CNAME.
  • ✓ Reverse DNS confirmed #30
    All 1 MX address have a PTR record that resolves back to them.

TLS

warn

no MTA-STS · no TLS-RPT · DANE on 0 of 1 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
mail.dnb.denone-

Checks

  • !
    Not configured
    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.
    #32
  • i
    Not configured
    TLS-RPT lets senders report TLS delivery problems to you. It is most useful together with MTA-STS or DANE.
    #35
  • i
    Not used
    No MX host publishes TLSA records. DANE lets senders verify your mail server's certificate through DNSSEC; it requires DNSSEC on the MX host's zone.
    #36

BIMI

info

No BIMI record

Checks

  • i
    Not configured
    BIMI shows your logo next to your mail in supporting mail clients. It requires DMARC enforcement.
    #38