Mail domain report: tno.nl

SPF

pass

SPF record published

Found

Record: v=spf1 ip4:134.221.1.0/24 ip4:46.31.48.0/21 ip4:84.241.159.211 ip6:2001:1690:23:332:10:77:32:16 include:spf.protection.outlook.com include:_spf.iprox.nl include:_spf-dc55.sapsf.eu include:_spf.emply.com -all
DNS lookups: 4 of 10
Void lookups: 0 of 2

Checks

✓ No deprecated ptr mechanism #1

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

SPF record needs 4 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

warn

p=quarantine (_dmarc.tno.nl)

Found

Record: v=DMARC1;p=quarantine;sp=none;fo=1;rua=mailto:beheer-tno-netwerk@tno.nl;ruf=mailto:beheer-tno-netwerk@tno.nl;
Found at: _dmarc.tno.nl

Tag	Value	Meaning
v	DMARC1	Version
p	quarantine	Policy
sp	none	Subdomain policy
rua	mailto:beheer-tno-netwerk@tno.nl	Aggregate report addresses
ruf	mailto:beheer-tno-netwerk@tno.nl	Failure report addresses
fo	1	Failure reporting options

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:beheer-tno-netwerk@tno.nl
!

Subdomains unprotected (sp=none)

DMARC subdomain policy is sp=none, so spoofed mail from subdomains is not blocked. Consider sp=quarantine or sp=reject.

#20
✓ Report addresses in own domain #29

All report addresses are in your own organizational domain.

DKIM

warn

Selectors: k1, selector1, selector2, s1, s2

Found

Selectors: k1, selector1, selector2, s1, s2
_domainkey: NOERROR

Selector	Key	Flags
k1	RSA 1024 bits
selector1	RSA 2048 bits
selector2	RSA 2048 bits
s1	RSA 2048 bits
s2	RSA 1024 bits

Checks

✓ Keys found: k1, selector1, selector2, s1, s2 #7

DKIM keys found for this domain with selectors: k1, selector1, selector2, s1, s2
!

1024-bit DKIM key

1024-bit RSA keys are the minimum and are considered weak today: k1 (1024 bits), s2 (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

pass

Signed, DS published at parent

Found

DNSKEY records: Yes (3)
DS at parent: Yes
Algorithms: RSASHA256 (8)
Key tags: 6490, 49157, 55834
Signatures valid until: 1 November 2026, 22:15 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 2026-11-01T22:15:24Z.

MX

warn

1 mail server

Found

Priority	Host	Records	Reverse DNS
0	tno-nl.a-v1.mx.microsoft	A 52.101.103.36 A 52.101.73.123 A 52.101.73.153 A 52.101.103.162 AAAA 2a01:111:f403:c967::8 AAAA 2a01:111:f403:ca21::c AAAA 2a01:111:f403:ca3c::8 AAAA 2a01:111:f403:ca09::24	mail-miypr05cu00104.inbound.protection.outlook.com ✓ mail-am6pr02cu00203.inbound.protection.outlook.com ✓ mail-as8pr05cu00401.inbound.protection.outlook.com ✓ mail-miypr03cu00202.inbound.protection.outlook.com ✓ mail-cpjpr04cu00100.inbound.protection.outlook.com ✓ mail-matpr04cu00204.inbound.protection.outlook.com ✓ mail-zrxpr05cu00100.inbound.protection.outlook.com ✓ mail-am6pr02cu00204.inbound.protection.outlook.com ✓

Checks

✓ 1 MX record #9

Found 1 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.
!

Single MX host, no backup

Only one MX record found. For better email reliability, consider adding at least one backup MX server.

#12
✓ At most 5 MX records #13

Found 1 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 1 of 1 MX hosts

Found

DANE (TLSA records)

MX host	TLSA	DNSSEC
tno-nl.a-v1.mx.microsoft	2 0 1 ea7a25255d111fc3… 2 0 1 c1ad7778796d20bc… 3 1 1 803f7447cc75b208… 3 1 1 54883cc5f1849331… 3 1 1 cfd68bde4129c00a…	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 1 MX host 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