ku.de

Checked 21 October 2026, 23:10 UTC · via 8.8.8.8
✗Problems found
23 passed 4 warnings 1 failed 1 info

SPF

pass

SPF record published

Found

Record
v=spf1 ip4:141.78.0.0/18 ip4:141.78.64.0/19 ip4:141.78.96.0/22 ip4:141.78.104.0/21 ip4:141.78.112.0/20 ip4:141.78.192.0/18 a:bvbvxmail.bib-bvb.de a:mailer02.zib.de ip4:5.9.79.165 ip4:159.69.247.208 ip4:23.88.47.24 include:mailgun.org ~all
DNS lookups
7 of 10
Void lookups
0 of 2

Checks

  • ✓ No deprecated ptr mechanism #1
    No ptr mechanism found in SPF record.
  • ✓ 7 of 10 DNS lookups #2
    SPF record needs 7 DNS lookups (limit is 10).
  • ✓ Ends with ~all #3
    SPF record properly uses ~all to restrict unauthorized senders.
  • ✓ Record published #6
    SPF record exists for this domain.
  • ✓ Single record #16
    Exactly one SPF record is published.
  • ✓ Valid syntax #25
    All SPF mechanisms and modifiers are valid.
  • ✓ No void lookups #26
    All include/redirect targets exist.
  • ✓ No overly broad IP ranges #27
    All ip4/ip6 ranges are narrow enough.

DMARC

fail

p=none (_dmarc.ku.de)

Found

Record
v=DMARC1; p=none; rua=mailto:dmarc-reports@ku.de
Found at
_dmarc.ku.de
TagValueMeaning
vDMARC1Version
pnonePolicy
ruamailto:dmarc-reports@ku.deAggregate report addresses

Checks

  • ✗
    Policy: none (monitoring only)
    DMARC policy is set to 'none', which only monitors but doesn't protect against spoofing. Consider upgrading to 'quarantine' or ideally 'reject'.
    #4
  • ✓ Record published #5
    DMARC record exists for this domain.
  • ✓ Valid syntax #17
    DMARC record syntax is valid.
  • ✓ Aggregate reports enabled #19
    Aggregate reports are sent to: mailto:dmarc-reports@ku.de
  • ✓ Report addresses in own domain #29
    All report addresses are in your own organizational domain.

DKIM

warn

No keys found under the checked selectors

Found

Selectors
None found
_domainkey
NOERROR

Checks

  • !
    No key under common selectors
    The _domainkey name exists but no DKIM key was found under the common selectors. Selectors are provider-specific; check yours with -selector.
    #7

DNSSEC

pass

Signed, DS published at parent

Found

DNSKEY records
Yes (2)
DS at parent
Yes
Algorithms
RSASHA512 (10)
Key tags
4487, 47166
Signatures valid until
14 November 2026, 20:34 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 2026-11-14 #21
    DNSKEY signatures are valid until 2026-11-14T20:34:17Z.

MX

warn

3 mail servers

Found

PriorityHostRecordsReverse DNS
10a1041.mx.srv.dfn.deA 194.95.232.37a1041.mx.srv.dfn.de ✓
10b1041.mx.srv.dfn.deA 194.95.234.37b1041.mx.srv.dfn.de ✓
10c1041.mx.srv.dfn.deA 194.95.238.37c1041.mx.srv.dfn.de ✓

Checks

  • ✓ 3 MX records #9
    Found 3 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: a1041.mx.srv.dfn.de, b1041.mx.srv.dfn.de, c1041.mx.srv.dfn.de
    #11
  • ✓ Redundant MX hosts #12
    Found 3 MX records, which provides redundancy for email delivery.
  • ✓ At most 5 MX records #13
    Found 3 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 3 MX addresss have a PTR record that resolves back to them.

TLS

warn

no MTA-STS · no TLS-RPT · DANE on 3 of 3 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
a1041.mx.srv.dfn.de3 0 1 9bec67f55f2afdb7…Yes
b1041.mx.srv.dfn.de3 0 1 9bec67f55f2afdb7…Yes
c1041.mx.srv.dfn.de3 0 1 9bec67f55f2afdb7…Yes

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
  • !
    Not configured
    MTA-STS or DANE is used without TLS-RPT, so you get no reports when senders fail to deliver because of TLS problems. Publish _smtp._tls TXT "v=TLSRPTv1; rua=mailto:...".
    #35
  • ✓ DANE on all MX hosts #36
    All 3 MX hosts publish DNSSEC-validated TLSA records.

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