tu-dortmund.de

Checked 22 October 2026, 00:41 UTC · via 8.8.8.8
✗Problems found
21 passed 3 warnings 1 failed 3 info

SPF

pass

SPF record published

Found

Record
v=spf1 ip4:93.190.66.6 ip4:129.217.0.16 ip4:129.217.4.40 ip4:129.217.128.0/24 ip4:129.217.131.0/24 ip4:195.66.99.135 ip4:62.75.247.44 ip4:212.227.89.57 ip4:217.160.226.166 ip4:82.165.193.1 ip4:85.25.144.9 ip4:54.194.192.132 ip4:87.79.30.25 ip4:87.79.30.30 ip4:91.217.141.0/24 ip4:128.176.118.0/25 ip4:129.217.231.64/26 ip4:185.134.242.25 ip6:2001:638:50d:1301::10 ip6:2001:638:50D:2000::/64 ip4:77.220.249.219 ip4:129.217.255.0/25 include:spf-eu.exlibrisgroup.com include:spf.crsend.com ip4:95.130.22.100 ip6:2a02:2940:0:c007::100 -all
DNS lookups
2 of 10
Void lookups
0 of 2

Checks

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

Found

Record
v=DMARC1; p=none; rua=mailto:dmarc@tu-dortmund.de
Found at
_dmarc.tu-dortmund.de
TagValueMeaning
vDMARC1Version
pnonePolicy
ruamailto:dmarc@tu-dortmund.deAggregate report addresses

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.
  • ✓ Aggregate reports enabled #19
    Aggregate reports are sent to: mailto:dmarc@tu-dortmund.de
  • ✓ Report addresses in own domain #29
    All report addresses are in your own organizational domain.

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

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

pass

2 mail servers

Found

PriorityHostRecordsReverse DNS
10esa3.itmc.tu-dortmund.deA 129.217.131.9 AAAA 2001:638:50d:2000::9esa3.itmc.tu-dortmund.de ✓ esa3.itmc.tu-dortmund.de ✓
10esa4.itmc.tu-dortmund.deA 129.217.131.14 AAAA 2001:638:50d:2000::14esa4.itmc.tu-dortmund.de ✓ esa4.itmc.tu-dortmund.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.
  • ✓ All hosts have IPv6 #11
    All MX records resolve to IPv6 addresses.
  • ✓ 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 4 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
esa3.itmc.tu-dortmund.denone-
esa4.itmc.tu-dortmund.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