Mail domain report: tu-bs.de

SPF

pass

SPF record published

Found

Record: v=spf1 ip4:134.169.4.128/26 ~all
DNS lookups: 0 of 10
Void lookups: 0 of 2

Checks

✓ No deprecated ptr mechanism #1

No ptr mechanism found in SPF record.
✓ 0 of 10 DNS lookups #2

SPF record needs 0 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-bs.de)

Found

Record: v=DMARC1;p=none;pct=100;rua=mailto:mailauth-reports@tu-braunschweig.de;ruf=mailto:mailauth-reports@tu-braunschweig.de;adkim=r;aspf=r
Found at: _dmarc.tu-bs.de
External report address: mailto:mailauth-reports@tu-braunschweig.de (not authorized)

Tag	Value	Meaning
v	DMARC1	Version
p	none	Policy
pct	100	Percentage of mail the policy applies to
rua	mailto:mailauth-reports@tu-braunschweig.de	Aggregate report addresses
ruf	mailto:mailauth-reports@tu-braunschweig.de	Failure report addresses
adkim	r	DKIM alignment (r = relaxed, s = strict)
aspf	r	SPF alignment (r = relaxed, s = strict)

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:mailauth-reports@tu-braunschweig.de
!

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:mailauth-reports@tu-braunschweig.de (needs tu-bs.de._report._dmarc.tu-braunschweig.de). Ask the report provider to publish the record, or check the address.

#29

DKIM

warn

Selectors: mail

Found

Selectors: mail
_domainkey: NOERROR

Selector	Key	Flags
mail	RSA 1024 bits

Checks

✓ Keys found: mail #7

DKIM keys found for this domain with selectors: mail
!

1024-bit DKIM key

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

3 mail servers

Found

Priority	Host	Records	Reverse DNS
10	a1991.mx.srv.dfn.de	A 194.95.232.151	a1991.mx.srv.dfn.de ✓
10	b1991.mx.srv.dfn.de	A 194.95.234.151	b1991.mx.srv.dfn.de ✓
10	c1991.mx.srv.dfn.de	A 194.95.238.151	c1991.mx.srv.dfn.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.
!

Hosts without IPv6

The following MX hosts could not be resolved to IPv6 addresses: a1991.mx.srv.dfn.de, b1991.mx.srv.dfn.de, c1991.mx.srv.dfn.de

#11
✓ 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.
✓ Reverse DNS confirmed #30

All 3 MX addresss have a PTR record that resolves back to them.

TLS

warn

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

Found

DANE (TLSA records)

MX host	TLSA	DNSSEC
a1991.mx.srv.dfn.de	3 0 1 9bec67f55f2afdb7…	Yes
b1991.mx.srv.dfn.de	3 0 1 9bec67f55f2afdb7…	Yes
c1991.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
✓ 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