gtue.de

Checked 21 October 2026, 22:41 UTC · via 8.8.8.8
✗Problems found
21 passed 4 warnings 1 failed 3 info

SPF

pass

SPF record published

Found

Record
v=spf1 ip4:212.87.147.230 ip4:185.38.52.60 ip4:144.208.214.205 ip4:140.86.0.0/16 ip4:160.34.0.0/16 ip4:51.89.73.208/28 ip4:147.135.249.48/28 ip4:54.37.79.226 ip4:149.96.132.2 ip4:148.139.105.17 ip4:199.91.136.28 ip4:148.139.104.17 ip4:149.96.220.2 ip4:103.23.65.2 ip4:103.23.66.26 ip4:103.23.67.26 ip4:149.96.133.2 ip4:149.96.2.26 ip4:149.96.1.26 ip4:148.139.104.16 ip4:199.91.140.28 ip4:149.96.221.2 ip4:148.139.105.16 ip4:103.23.64.2 ip4:149.96.195.2 ip4:149.96.194.2 ip4:37.98.232.2 ip4:199.91.140.26 ip4:37.98.235.2 ip4:37.98.234.2 ip4:148.139.0.31 ip4:199.91.141.22 ip4:199.91.139.24 ip4:199.91.137.2 ip4:199.91.141.23 ip4:149.96.13.2 ip4:148.139.2.2 ip4:199.91.139.23 ip4:199.91.139.22 ip4:37.98.232.12 ip4:148.139.1.2 ip4:148.139.1.31 ip4:148.139.3.2 ip4:199.91.139.145 ip4:199.91.136.28 ip4:199.91.136.26 ip4:199.91.137.26 ip4:199.91.140.28 ip4:199.91.141.145 ip4:149.96.14.2 ip4:199.91.141.24 ip4:37.98.232.26 ip4:148.139.0.2 ip4:199.91.136.28 ip4:148.139.124.22 ip4:149.96.6.3 ip4:149.96.5.7 ip4:148.139.124.23 ip4:149.96.5.6 ip4:149.96.5.2 ip4:148.139.125.24 ip4:149.96.6.2 ip4:149.96.6.209 ip4:148.139.124.24 ip4:148.139.125.22 ip4:149.96.5.3 ip4:199.91.140.28 ip4:149.96.5.209 ip4:148.139.125.21 ip4:149.96.6.7 ip4:148.139.124.21 ip4:148.139.125.23 ip4:149.96.6.6 ip4:86.109.249.96/27 include:spf.protection.outlook.com include:spf.mailjet.com include:spf_c.oracle.com include:spf_a.oracle.com include:spf.hornetsecurity.com ~all
DNS lookups
5 of 10
Void lookups
0 of 2

Checks

  • ✓ No deprecated ptr mechanism #1
    No ptr mechanism found in SPF record.
  • ✓ 5 of 10 DNS lookups #2
    SPF record needs 5 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.gtue.de)

Found

Record
v=DMARC1;p=none;adkim=r;aspf=r;rua=mailto:dmarc@gtue.de
Found at
_dmarc.gtue.de
TagValueMeaning
vDMARC1Version
pnonePolicy
ruamailto:dmarc@gtue.deAggregate report addresses
adkimrDKIM alignment (r = relaxed, s = strict)
aspfrSPF alignment (r = relaxed, s = strict)

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@gtue.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

warn

Signed, DS published at parent

Found

DNSKEY records
Yes (3)
DS at parent
Yes
Algorithms
ECDSAP256SHA256 (13)
Key tags
59416, 27984, 5641
Signatures valid until
22 October 2026, 02:00 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 expire in 3h0m0s
    DNSKEY signatures expire at 2026-10-22T02:00:00Z (in 3h0m0s). Check that re-signing works.
    #21

MX

warn

4 mail servers

Found

PriorityHostRecordsReverse DNS
10mx01.hornetsecurity.comA 94.100.132.8mx01.hornetsecurity.com ✓
20mx02.hornetsecurity.comA 94.100.136.8mx02.hornetsecurity.com ✓
30mx03.hornetsecurity.comA 94.100.134.8mx03.hornetsecurity.com ✓
40mx04.hornetsecurity.comA 94.100.136.7mx04.hornetsecurity.com ✓

Checks

  • ✓ 4 MX records #9
    Found 4 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: mx01.hornetsecurity.com, mx02.hornetsecurity.com, mx03.hornetsecurity.com, mx04.hornetsecurity.com
    #11
  • ✓ Redundant MX hosts #12
    Found 4 MX records, which provides redundancy for email delivery.
  • ✓ At most 5 MX records #13
    Found 4 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 4 MX addresss have a PTR record that resolves back to them.

TLS

warn

no MTA-STS · no TLS-RPT · DANE on 0 of 4 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
mx01.hornetsecurity.comnone-
mx02.hornetsecurity.comnone-
mx03.hornetsecurity.comnone-
mx04.hornetsecurity.comnone-

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