posteo.de

Checked 21 October 2026, 23:50 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 ip4:185.67.36.0/23 ip6:2a05:bc0:1000::/47 ~all
DNS lookups
0 of 10
Void lookups
0 of 2

Checks

  • ✓ No deprecated ptr mechanism #1
    No ptr mechanism found in SPF record.
  • ✓ 0 of 10 DNS lookups #2
    SPF record needs 0 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.posteo.de)

Found

Record
v=DMARC1; p=none; sp=quarantine; adkim=s; aspf=s
Found at
_dmarc.posteo.de
TagValueMeaning
vDMARC1Version
pnonePolicy
spquarantineSubdomain policy
adkimsDKIM alignment (r = relaxed, s = strict)
aspfsSPF 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.
  • !
    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

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
53881, 23244
Signatures valid until
29 October 2026, 00:00 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 valid until 2026-10-29 #21
    DNSKEY signatures are valid until 2026-10-29T00:00:00Z.

MX

warn

4 mail servers

Found

PriorityHostRecordsReverse DNS
10mx01.posteo.deA 185.67.36.62 A 185.67.36.61mx01.posteo.de ✓ mx01.posteo.de ✓
10mx02.posteo.deA 185.67.36.73mx02.posteo.de ✓
10mx03.posteo.deA 185.67.36.63 A 185.67.36.70mx03.posteo.de ✓ mx03.posteo.de ✓
10mx04.posteo.deA 185.67.36.71 A 185.67.36.64mx04.posteo.de ✓ mx04.posteo.de ✓

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.posteo.de, mx02.posteo.de, mx03.posteo.de, mx04.posteo.de
    #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 7 MX addresss have a PTR record that resolves back to them.

TLS

pass

MTA-STS enforce · TLS-RPT · DANE on 4 of 4 MX hosts

Found

MTA-STS record
v=STSv1; id=20251202110430Z
Policy URL
https://mta-sts.posteo.de/.well-known/mta-sts.txt
Mode
enforce
Allowed MX
mx01.posteo.de, mx02.posteo.de, mx03.posteo.de, mx04.posteo.de, posteo.de
Max age
1209600 seconds
TLS-RPT record
v=TLSRPTv1; rua=mailto:tlsrpt@posteo.de

DANE (TLSA records)

MX hostTLSADNSSEC
mx01.posteo.de3 1 1 0becb1af349fc7c5… 3 1 1 a73a9adb16bd5a41… 3 1 1 2ad38769dc6a92ed… 3 1 1 2a2413f46c232908… 3 1 1 b2305f6446e9cfae… 3 1 1 13815b2c03f7bd63…Yes
mx02.posteo.de3 1 1 a73a9adb16bd5a41… 3 1 1 b2305f6446e9cfae… 3 1 1 13815b2c03f7bd63… 3 1 1 0becb1af349fc7c5… 3 1 1 2ad38769dc6a92ed… 3 1 1 2a2413f46c232908…Yes
mx03.posteo.de3 1 1 13815b2c03f7bd63… 3 1 1 b2305f6446e9cfae… 3 1 1 0becb1af349fc7c5… 3 1 1 2a2413f46c232908… 3 1 1 2ad38769dc6a92ed… 3 1 1 a73a9adb16bd5a41…Yes
mx04.posteo.de3 1 1 2a2413f46c232908… 3 1 1 a73a9adb16bd5a41… 3 1 1 0becb1af349fc7c5… 3 1 1 2ad38769dc6a92ed… 3 1 1 b2305f6446e9cfae… 3 1 1 13815b2c03f7bd63…Yes

Checks

  • ✓ Record published #32
    MTA-STS record found with id 20251202110430Z.
  • ✓ Policy enforced #33
    The MTA-STS policy is enforced and cached for 336h0m0s.
  • ✓ All MX hosts covered #34
    Every MX host matches an mx: line of the MTA-STS policy.
  • ✓ Reports enabled #35
    TLS reports are sent to: mailto:tlsrpt@posteo.de
  • ✓ DANE on all MX hosts #36
    All 4 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