hfmt-hamburg.de

Checked 21 October 2026, 22:50 UTC · via 8.8.8.8
✗Problems found
19 passed 3 warnings 1 failed 2 info

SPF

info

SPF record published

Found

Record
v=spf1 redirect=_spf.tuhh.de
DNS lookups
1 of 10
Void lookups
0 of 2

Checks

  • ✓ No deprecated ptr mechanism #1
    No ptr mechanism found in SPF record.
  • ✓ 1 of 10 DNS lookups #2
    SPF record needs 1 DNS lookups (limit is 10).
  • i
    Delegated via redirect
    SPF record has no 'all' mechanism but redirects to _spf.tuhh.de, whose policy applies.
    #3
  • ✓ 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

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

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
RSASHA256 (8)
Key tags
64531, 13444
Signatures valid until
10 November 2026, 11:09 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 2026-11-10 #21
    DNSKEY signatures are valid until 2026-11-10T11:09:38Z.

MX

pass

3 mail servers

Found

PriorityHostRecordsReverse DNS
5smtp4.rz.tu-harburg.deA 134.28.205.34 AAAA 2001:638:702:20aa::205:34smtp4.rz.tu-harburg.de ✓ smtp4.rz.tu-harburg.de ✓
15smtp5.rz.tu-harburg.deA 134.28.205.35 AAAA 2001:638:702:20aa::205:35smtp5.rz.tu-harburg.de ✓ smtp5.rz.tu-harburg.de ✓
25smtp3.rz.tu-harburg.deA 134.28.205.37 AAAA 2001:638:702:20aa::205:37smtp3.rz.tu-harburg.de ✓ smtp3.rz.tu-harburg.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.
  • ✓ All hosts have IPv6 #11
    All MX records resolve to IPv6 addresses.
  • ✓ 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 6 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
smtp4.rz.tu-harburg.de2 0 1 5b678dc44095a528…Yes
smtp5.rz.tu-harburg.de2 0 1 5b678dc44095a528…Yes
smtp3.rz.tu-harburg.de2 0 1 5b678dc44095a528…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