jo-so.de

Checked 21 October 2026, 23:01 UTC · via 8.8.8.8
✗Problems found
15 passed 5 warnings 4 failed 1 info

SPF

pass

SPF record published

Found

Record
v=spf1 mx a:s1.jo-so.de a:uucp.gnuu.de -all
DNS lookups
3 of 10
Void lookups
0 of 2

Checks

  • ✓ No deprecated ptr mechanism #1
    No ptr mechanism found in SPF record.
  • ✓ 3 of 10 DNS lookups #2
    SPF record needs 3 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

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

fail

No keys found under the checked selectors

Found

Selectors
None found
_domainkey
NXDOMAIN

Checks

  • ✗
    No DKIM keys published
    _domainkey.jo-so.de does not exist (NXDOMAIN), so no DKIM keys are published. DKIM helps prevent email spoofing. Configure DKIM with your email service provider.
    #7

DNSSEC

fail

Signed, but no DS at parent

Found

DNSKEY records
Yes (3)
DS at parent
No
Algorithms
RSASHA256 (8)
Key tags
44875, 55295, 48724
Signatures valid until
20 October 2026, 09:50 UTC

Checks

  • !
    Signed, but no DS at parent
    The zone is signed (DNSKEY present) but the parent has no DS record, so the chain of trust is incomplete. Publish the DS record at your registrar.
    #8
  • ✗
    Signatures expired
    DNSKEY signatures expired at 2026-10-20T09:50:00Z. Validating resolvers will fail to resolve this domain.
    #21

MX

warn

1 mail server

Found

PriorityHostRecordsReverse DNS
100jo-so.deA 37.221.195.157 AAAA 2a03:4000:8:213::1s1.jo-so.de ✓ ptr.0001.0000.0000.0000.0213.0008.4000.2a03.static.yourvserver.net (does not resolve back)

Checks

  • ✓ 1 MX record #9
    Found 1 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.
  • !
    Single MX host, no backup
    Only one MX record found. For better email reliability, consider adding at least one backup MX server.
    #12
  • ✓ At most 5 MX records #13
    Found 1 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 does not match
    The PTR name of these addresses does not resolve back to the same address: 2a03:4000:8:213::1 -> ptr.0001.0000.0000.0000.0213.0008.4000.2a03.static.yourvserver.net.
    #30

TLS

fail

no MTA-STS · no TLS-RPT · DANE on 1 of 1 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
jo-so.de2 1 1 2e8307068b6db620… 2 1 1 6ebcefb4210b0886…No

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
  • ✗
    TLSA records not DNSSEC-validated
    These MX hosts publish TLSA records that the resolver could not validate with DNSSEC, so senders ignore them or, if validation fails, may refuse delivery: jo-so.de.
    #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