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posteo.de

Checked 2026-10-21 23:50 UTC · first added 2026-10-21
✗Problems found Score 78 of 100

Domain & DNS

warn

29 passed 1 warn 0 failed

Areas

iRegistration ✓Delegation iNameservers ✓SOA !DNSSEC ✓Records

Problems

  • !
    NSEC3 with extra iterations or salt
    DNSSEC · NSEC3 uses 20 iterations and a 8-byte salt. RFC 9276 recommends 0 iterations and no salt: extra iterations cost resolvers CPU and add no real protection, and some validators treat high counts as insecure.
    #31

Recent checks

!

Full report

Domain & DNS report for posteo.de ›

Mail

fail

25 passed 3 warn 1 failed

Areas

✓SPF ✗DMARC !DKIM ✓DNSSEC !MX ✓TLS iBIMI

Problems

  • ✗
    Policy: none (monitoring only)
    DMARC · DMARC policy is set to 'none', which only monitors but doesn't protect against spoofing. Consider upgrading to 'quarantine' or ideally 'reject'.
    #4
  • !
    No key under common selectors
    DKIM · The _domainkey name exists but no DKIM key was found under the common selectors. Selectors are provider-specific; check yours with -selector.
    #7
  • !
    Hosts without IPv6
    MX · The following MX hosts could not be resolved to IPv6 addresses: mx01.posteo.de, mx02.posteo.de, mx03.posteo.de, mx04.posteo.de
    #11
  • !
    No aggregate reports (rua)
    DMARC · DMARC record has no rua tag, so you receive no aggregate reports about who sends mail as your domain. Add rua=mailto:...
    #19

Recent checks

✗

Full report

Mail report for posteo.de ›