t-online.de

Checked 22 October 2026, 00:31 UTC · via 8.8.8.8
✗Problems found
23 passed 4 warnings 1 failed 2 info

SPF

pass

SPF record published

Found

Record
v=spf1 ip4:194.25.134.16/28 ip4:194.25.134.80/28 ~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.t-online.de)

Found

Record
v=DMARC1; p=none; rua=mailto:dmarc-rua@rx.t-online.de
Found at
_dmarc.t-online.de
TagValueMeaning
vDMARC1Version
pnonePolicy
ruamailto:dmarc-rua@rx.t-online.deAggregate report addresses

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-rua@rx.t-online.de
  • ✓ Report addresses in own domain #29
    All report addresses are in your own organizational domain.

DKIM

warn

No keys found under the checked selectors

Found

Selectors
None found
_domainkey
NOERROR

Checks

  • !
    No key under common selectors
    The _domainkey name exists but no DKIM key was found under the common selectors. Selectors are provider-specific; check yours with -selector.
    #7

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

4 mail servers

Found

PriorityHostRecordsReverse DNS
10mx00.t-online.deA 194.25.134.8mx00.t-online.de ✓
10mx01.t-online.deA 194.25.134.72mx01.t-online.de ✓
10mx02.t-online.deA 194.25.134.9mx02.t-online.de ✓
10mx03.t-online.deA 194.25.134.73mx03.t-online.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.
  • !
    Hosts without IPv6
    The following MX hosts could not be resolved to IPv6 addresses: mx00.t-online.de, mx01.t-online.de, mx02.t-online.de, mx03.t-online.de
    #11
  • ✓ 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 4 MX addresss have a PTR record that resolves back to them.

TLS

warn

MTA-STS testing · TLS-RPT · DANE on 0 of 4 MX hosts

Found

MTA-STS record
v=STSv1;id=20250815115500Z;
Policy URL
https://mta-sts.t-online.de/.well-known/mta-sts.txt
Mode
testing
Allowed MX
mx01.t-online.de, mx00.t-online.de, mx03.t-online.de, mx02.t-online.de
Max age
604800 seconds
TLS-RPT record
v=TLSRPTv1; rua=mailto:smtp-tlsrpt@rx.t-online.de

DANE (TLSA records)

MX hostTLSADNSSEC
mx00.t-online.denone-
mx01.t-online.denone-
mx02.t-online.denone-
mx03.t-online.denone-

Checks

  • ✓ Record published #32
    MTA-STS record found with id 20250815115500Z.
  • !
    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:smtp-tlsrpt@rx.t-online.de
  • 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