uni-freiburg.de

Checked 22 October 2026, 00:50 UTC · via 8.8.8.8

✗Problems found

18 passed 5 warnings 1 failed 2 info

SPF

info

SPF record published

Found

Record: v=spf1 redirect=_spf.uni-freiburg.de
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).
i

Delegated via redirect

SPF record has no 'all' mechanism but redirects to _spf.uni-freiburg.de, whose policy applies.

#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

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

warn

Selectors: s1

Found

Selectors: s1
_domainkey: NOERROR

Selector	Key	Flags
s1	RSA 1024 bits

Checks

✓ Keys found: s1 #7

DKIM keys found for this domain with selectors: s1
!

1024-bit DKIM key

1024-bit RSA keys are the minimum and are considered weak today: s1 (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

pass

4 mail servers

Found

Priority	Host	Records	Reverse DNS
10	mail.uni-freiburg.de	A 132.230.2.46 AAAA 2001:7c0:2500:4::25:0	mail.uni-freiburg.de ✓ mail.uni-freiburg.de ✓
10000	a1421.mx.srv.dfn.de	A 194.95.232.79 AAAA 2001:638:d:c301:acdc:1979:2:2f	a1421.mx.srv.dfn.de ✓ a1421.mx.srv.dfn.de ✓
10000	b1421.mx.srv.dfn.de	A 194.95.234.79 AAAA 2001:638:d:c302:acdc:1979:2:2f	b1421.mx.srv.dfn.de ✓ b1421.mx.srv.dfn.de ✓
10000	c1421.mx.srv.dfn.de	A 194.95.238.79 AAAA 2001:638:d:c303:acdc:1979:2:2f	c1421.mx.srv.dfn.de ✓ c1421.mx.srv.dfn.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.
✓ All hosts have IPv6 #11

All MX records resolve to IPv6 addresses.
✓ 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 8 MX addresss have a PTR record that resolves back to them.

TLS

warn

no MTA-STS · no TLS-RPT · DANE on 3 of 4 MX hosts

Found

DANE (TLSA records)

MX host	TLSA	DNSSEC
mail.uni-freiburg.de	none	-
a1421.mx.srv.dfn.de	3 0 1 9bec67f55f2afdb7…	Yes
b1421.mx.srv.dfn.de	3 0 1 9bec67f55f2afdb7…	Yes
c1421.mx.srv.dfn.de	3 0 1 9bec67f55f2afdb7…	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
!

Not all MX hosts use DANE

These MX hosts publish no TLSA records, so mail to them is not protected by DANE: mail.uni-freiburg.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