duisburg.de

Checked 21 October 2026, 22:15 UTC · via 8.8.8.8
✗Problems found
15 passed 6 warnings 1 failed 3 info

SPF

fail

No SPF record found

Checks

  • ✗
    No SPF record
    No SPF record was found for this domain. SPF is important for preventing email spoofing. Add an SPF record to specify which servers are authorized to send email for your domain.
    #6

DMARC

warn

p=quarantine (_dmarc.duisburg.de)

Found

Record
v=DMARC1; p=quarantine; rua=mailto:postmaster@duit.de,mailto:operational-security@stadt-duisburg.de
Found at
_dmarc.duisburg.de
External report address
mailto:postmaster@duit.de (not authorized)
External report address
mailto:operational-security@stadt-duisburg.de (not authorized)
TagValueMeaning
vDMARC1Version
pquarantinePolicy
ruamailto:postmaster@duit.de,mailto:operational-security@stadt-duisburg.deAggregate report addresses

Checks

  • !
    Policy: quarantine
    DMARC policy is set to 'quarantine'. Consider upgrading to 'reject' for stronger protection once you've verified legitimate emails are passing authentication.
    #4
  • ✓ Record published #5
    DMARC record exists for this domain.
  • ✓ Valid syntax #17
    DMARC record syntax is valid.
  • ✓ Applies to 100% of mail #18
    DMARC policy applies to all failing mail.
  • ✓ Aggregate reports enabled #19
    Aggregate reports are sent to: mailto:postmaster@duit.de, mailto:operational-security@stadt-duisburg.de
  • ✓ Subdomain policy: quarantine #20
    Subdomains are covered by policy 'quarantine'.
  • !
    Report address not authorized
    These report addresses are in another domain that has not agreed to receive your reports, so receivers will not send them: mailto:postmaster@duit.de (needs duisburg.de._report._dmarc.duit.de); mailto:operational-security@stadt-duisburg.de (needs duisburg.de._report._dmarc.stadt-duisburg.de). Ask the report provider to publish the record, or check the address.
    #29

DKIM

warn

Selectors: k1

Found

Selectors
k1
_domainkey
NOERROR
SelectorKeyFlags
k1RSA 1024 bits

Checks

  • ✓ Keys found: k1 #7
    DKIM keys found for this domain with selectors: k1
  • !
    1024-bit DKIM key
    1024-bit RSA keys are the minimum and are considered weak today: k1 (1024 bits). Rotate to a 2048-bit key.
    #23
  • ✓ No problematic flags #24
    No keys in test mode, revoked, or limited to SHA-1.

DNSSEC

warn

Not signed

Found

DNSKEY records
No (0)
DS at parent
No

Checks

  • !
    Not enabled
    DNSSEC is not enabled for this domain. Consider enabling DNSSEC to protect against DNS spoofing attacks.
    #8

MX

warn

2 mail servers

Found

PriorityHostRecordsReverse DNS
10mx231.duit.deA 185.155.188.50mx231.duit.de ✓
50mx20.duit.deA 185.155.188.51mx20.duit.de ✓

Checks

  • ✓ 2 MX records #9
    Found 2 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: mx231.duit.de, mx20.duit.de
    #11
  • ✓ Redundant MX hosts #12
    Found 2 MX records, which provides redundancy for email delivery.
  • ✓ At most 5 MX records #13
    Found 2 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 2 MX addresss have a PTR record that resolves back to them.

TLS

warn

no MTA-STS · no TLS-RPT · DANE on 0 of 2 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
mx231.duit.denone-
mx20.duit.denone-

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