Mail domain report: concertgebouw.nl

SPF

info

SPF record published

Found

Record: v=spf1 redirect=_sog58p08n.sdmarc.net
DNS lookups: 5 of 10
Void lookups: 0 of 2

Checks

✓ No deprecated ptr mechanism #1

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

SPF record needs 5 DNS lookups (limit is 10).
i

Delegated via redirect

SPF record has no 'all' mechanism but redirects to _sog58p08n.sdmarc.net, 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

pass

p=reject (_dmarc.concertgebouw.nl)

Found

Record: v=DMARC1; p=reject; rua=mailto:a.og58p08n@sdmarc.net; ruf=mailto:f.og58p08n@sdmarc.net; adkim=r; aspf=r
Found at: _dmarc.concertgebouw.nl
External report address: mailto:a.og58p08n@sdmarc.net (authorized)
External report address: mailto:f.og58p08n@sdmarc.net (authorized)

Tag	Value	Meaning
v	DMARC1	Version
p	reject	Policy
rua	mailto:a.og58p08n@sdmarc.net	Aggregate report addresses
ruf	mailto:f.og58p08n@sdmarc.net	Failure report addresses
adkim	r	DKIM alignment (r = relaxed, s = strict)
aspf	r	SPF alignment (r = relaxed, s = strict)

Checks

✓ Policy: reject #4

DMARC policy is set to 'reject', which provides the strongest protection against email spoofing.
✓ 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:a.og58p08n@sdmarc.net
✓ Subdomain policy: reject #20

Subdomains are covered by policy 'reject'.
✓ External report addresses authorized #29

Report addresses in other domains have published their authorization.

DKIM

warn

Selectors: selector1, selector2

Found

Selectors: selector1, selector2
_domainkey: NOERROR

Selector	Key	Flags
selector1	RSA 1024 bits
selector2	RSA 1024 bits

Checks

✓ Keys found: selector1, selector2 #7

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

1024-bit DKIM key

1024-bit RSA keys are the minimum and are considered weak today: selector1 (1024 bits), selector2 (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 (1)
DS at parent: Yes
Algorithms: RSASHA256 (8)
Key tags: 44347
Signatures valid until: 29 October 2026, 00:00 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 2026-10-29 #21

DNSKEY signatures are valid until 2026-10-29T00:00:00Z.

MX

warn

1 mail server

Found

Priority	Host	Records	Reverse DNS
10	concertgebouw-nl.mail.protection.outlook.com	A 52.101.185.114 A 52.101.185.21 A 52.101.181.153 A 52.101.209.31 AAAA 2a01:111:f403:ca09::20 AAAA 2a01:111:f403:ca38::a AAAA 2a01:111:f403:ca09::26 AAAA 2a01:111:f403:ca21::10	mail-zrxpr04cu00102.inbound.protection.outlook.com ✓ mail-zrxpr05cu00105.inbound.protection.outlook.com ✓ mail-wa4pr04cu00101.inbound.protection.outlook.com ✓ mail-cpjpr05cu00207.inbound.protection.outlook.com ✓ mail-as8pr05cu00400.inbound.protection.outlook.com ✓ mail-wa4pr05cu00102.inbound.protection.outlook.com ✓ mail-am8pr83cu00106.inbound.protection.outlook.com ✓ mail-matpr05cu00100.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

MTA-STS testing · TLS-RPT · DANE on 0 of 1 MX hosts

Found

MTA-STS record: v=STSv1; id=1749561042
Policy URL: https://mta-sts.concertgebouw.nl/.well-known/mta-sts.txt
Mode: testing
Allowed MX: concertgebouw-nl.mail.protection.outlook.com
Max age: 604800 seconds
TLS-RPT record: v=TLSRPTv1; rua=mailto:reports@sendmarc.net

DANE (TLSA records)

MX host	TLSA	DNSSEC
concertgebouw-nl.mail.protection.outlook.com	none	-

Checks

✓ Record published #32

MTA-STS record found with id 1749561042.
!

Policy in testing mode

With mode: testing, senders only report TLS problems (via TLS-RPT) and still deliver without TLS. Switch to mode: enforce once reports are clean.

#33
✓ All MX hosts covered #34

Every MX host matches an mx: line of the MTA-STS policy.
✓ Reports enabled #35

TLS reports are sent to: mailto:reports@sendmarc.net
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