ntr.nl

Checked 21 October 2026, 21:23 UTC · via 8.8.8.8
✗Problems found
24 passed 3 warnings 1 failed 3 info

SPF

pass

SPF record published

Found

Record
v=spf1 include:spf.protection.outlook.com include:spf.mandrillapp.com include:spf.flowmailer.net ip4:145.58.241.25 ip4:145.58.26.176/28 ip4:145.58.30.176/28 ip6:2a02:458:101:30::/64 ip6:2a02:458:101:26::/64 include:_spf.exsilia.net include:spf.courseware.nl ip4:80.84.235.70 include:virtual.dmdelivery.com -all
DNS lookups
7 of 10
Void lookups
0 of 2

Checks

  • ✓ No deprecated ptr mechanism #1
    No ptr mechanism found in SPF record.
  • ✓ 7 of 10 DNS lookups #2
    SPF record needs 7 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.ntr.nl)

Found

Record
v=DMARC1; p=none; rua=mailto:dmarc@inbound.flowmailer.net; ruf=mailto:dmarc@inbound.flowmailer.net; fo=1
Found at
_dmarc.ntr.nl
External report address
mailto:dmarc@inbound.flowmailer.net (authorized)
TagValueMeaning
vDMARC1Version
pnonePolicy
ruamailto:dmarc@inbound.flowmailer.netAggregate report addresses
rufmailto:dmarc@inbound.flowmailer.netFailure report addresses
fo1Failure reporting options

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:dmarc@inbound.flowmailer.net
  • ✓ External report addresses authorized #29
    Report addresses in other domains have published their authorization.

DKIM

warn

Selectors: selector1

Found

Selectors
selector1
_domainkey
NOERROR
SelectorKeyFlags
selector1RSA 1024 bits

Checks

  • ✓ Keys found: selector1 #7
    DKIM keys found for this domain with selectors: selector1
  • !
    1024-bit DKIM key
    1024-bit RSA keys are the minimum and are considered weak today: selector1 (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
ECDSAP256SHA256 (13)
Key tags
22515
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

PriorityHostRecordsReverse DNS
8ntr-nl.mail.protection.outlook.comA 52.101.73.145 A 52.101.68.8 A 52.101.68.39 A 52.101.91.153 AAAA 2a01:111:f403:ca21::8 AAAA 2a01:111:f403:c967::8 AAAA 2a01:111:f403:ca38::a AAAA 2a01:111:f403:ca3c::amail-am6pr02cu00301.inbound.protection.outlook.com ✓ mail-du0pr03cu00100.inbound.protection.outlook.com ✓ mail-db7pr03cu00607.inbound.protection.outlook.com ✓ mail-matpr04cu00101.inbound.protection.outlook.com ✓ mail-matpr04cu00100.inbound.protection.outlook.com ✓ mail-cpjpr04cu00100.inbound.protection.outlook.com ✓ mail-wa4pr05cu00102.inbound.protection.outlook.com ✓ mail-zrxpr07cu00102.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 0 of 1 MX hosts

Found

DANE (TLSA records)

MX hostTLSADNSSEC
ntr-nl.mail.protection.outlook.comnone-

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
  • i
    Not configured
    TLS-RPT lets senders report TLS delivery problems to you. It is most useful together with MTA-STS or DANE.
    #35
  • 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