dfn.de

Checked 21 October 2026, 22:14 UTC · via 8.8.8.8
✗Problems found
25 passed 3 warnings 1 failed 1 info

SPF

pass

SPF record published

Found

Record
v=spf1 include:_spf.s1004.mx.srv.dfn.de a:deneb.dfn.de include:_spf.dfn-cert.de include:_spft.telekom.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.dfn.de)

Found

Record
v=DMARC1; p=none
Found at
_dmarc.dfn.de
TagValueMeaning
vDMARC1Version
pnonePolicy

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.
  • !
    No aggregate reports (rua)
    DMARC record has no rua tag, so you receive no aggregate reports about who sends mail as your domain. Add rua=mailto:...
    #19

DKIM

pass

Selectors: s1, s2

Found

Selectors
s1, s2
_domainkey
NOERROR
SelectorKeyFlags
s1revoked
s2RSA 2048 bits

Checks

  • ✓ Keys found: s1, s2 #7
    DKIM keys found for this domain with selectors: s1, s2
  • ✓ Strong keys #23
    DKIM keys are strong enough: s2: RSA 2048 bits.
  • ✓ No problematic flags #24
    No test mode or SHA-1-only keys. Revoked keys (empty p=), which is fine after a key rotation: s1.

DNSSEC

pass

Signed, DS published at parent

Found

DNSKEY records
Yes (2)
DS at parent
Yes
Algorithms
ECDSAP256SHA256 (13)
Key tags
52345, 15867
Signatures valid until
5 November 2026, 15:27 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 2026-11-05 #21
    DNSKEY signatures are valid until 2026-11-05T15:27:27Z.

MX

pass

3 mail servers

Found

PriorityHostRecordsReverse DNS
10a1001.mx.srv.dfn.deA 194.95.233.3 AAAA 2001:638:d:c301:acdc:1979:2:1a1001.mx.srv.dfn.de ✓ a1001.mx.srv.dfn.de ✓
10b1001.mx.srv.dfn.deA 194.95.235.3 AAAA 2001:638:d:c302:acdc:1979:2:1b1001.mx.srv.dfn.de ✓ b1001.mx.srv.dfn.de ✓
10c1001.mx.srv.dfn.deA 194.95.239.3 AAAA 2001:638:d:c303:acdc:1979:2:1c1001.mx.srv.dfn.de ✓ c1001.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.
  • ✓ 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
a1001.mx.srv.dfn.de3 0 1 9bec67f55f2afdb7…Yes
b1001.mx.srv.dfn.de3 0 1 9bec67f55f2afdb7…Yes
c1001.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