stusta.de

Checked 22 October 2026, 00:31 UTC · via 8.8.8.8
✗Problems found
25 passed 3 warnings 1 failed 2 info

SPF

warn

SPF record published

Found

Record
v=spf1 a:mail.stusta.mhn.de include:_spf.mail.lrz.de ?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 (neutral)
    SPF record uses ?all (neutral), which gives no protection against unauthorized senders. Use -all or ~all instead.
    #3
  • ✓ 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.stusta.de)

Found

Record
v=DMARC1; p=none; rua=mailto:mailreport@stusta.de
Found at
_dmarc.stusta.de
TagValueMeaning
vDMARC1Version
pnonePolicy
ruamailto:mailreport@stusta.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:mailreport@stusta.de
  • ✓ Report addresses in own domain #29
    All report addresses are in your own organizational domain.

DKIM

pass

Selectors: default

Found

Selectors
default
_domainkey
NOERROR
SelectorKeyFlags
defaultRSA 4096 bitsh=sha256

Checks

  • ✓ Keys found: default #7
    DKIM keys found for this domain with selectors: default
  • ✓ Strong keys #23
    DKIM keys are strong enough: default: RSA 4096 bits.
  • ✓ No problematic flags #24
    No keys in test mode, revoked, or limited to SHA-1.

DNSSEC

pass

Signed, DS published at parent

Found

DNSKEY records
Yes (2)
DS at parent
Yes
Algorithms
RSASHA256 (8)
Key tags
47579, 59215
Signatures valid until
1 November 2026, 21:12 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 2026-11-01 #21
    DNSKEY signatures are valid until 2026-11-01T21:12:42Z.

MX

info

3 mail servers

Found

PriorityHostRecordsReverse DNS
20mail.stusta.mhn.deA 141.84.69.5 AAAA 2001:4ca0:200:3:200:5efe:8d54:4505mail.stusta.mhn.de ✓ lookup failed
50mailrelay1.lrz.deA 129.187.255.133 AAAA 2001:4ca0:0:103::81bb:ff85mailrelay1.lrz.de ✓ mailrelay1.lrz.de ✓
50mailrelay2.lrz.deA 129.187.255.134 AAAA 2001:4ca0:0:103::81bb:ff86mailrelay2.lrz.de ✓ mailrelay2.lrz.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.
  • i
    Could not be checked
    The reverse lookup failed for: 2001:4ca0:200:3:200:5efe:8d54:4505.
    #30

TLS

warn

no MTA-STS · no TLS-RPT · DANE on 3 of 3 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
mail.stusta.mhn.de3 1 1 665ed2f76e88cd90… 3 1 1 d5905bbdec3ced21…Yes
mailrelay1.lrz.de3 1 1 7579e53a665be8c1…Yes
mailrelay2.lrz.de3 1 1 8de81c8f4a56e829…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