spamhaus public resolver problem (again?)

Discussion in 'Installation/Configuration' started by brt, May 14, 2025.

  1. brt

    brt New Member

    Today I started seeing this error in my mail logs:

    Code:
    blocked using zen.spamhaus.org; Error: open resolver; https://check.spamhaus.org/returnc/pub/2a01:4f8:272:5193::2/; 
    I’ve confirmed that my local DNS server (127.0.0.1 in /etc/resolv.conf) only resolves our own zones and does not offer recursion to the public. Everything appears to be set up correctly.

    Interestingly, this only affected our servers at Hetzner - servers in other locations were unaffected.

    I removed zen.spamhaus.org from the ISPConfig RBL settings, and mail delivery resumed (we also have Rspamd in place).

    Could this have been an issue on Spamhaus’s side, or is there something I’m overlooking in my configuration? Any insights would be greatly appreciated.
     
  2. till

    till Super Moderator Staff Member ISPConfig Developer

    I guess Spamhaus blocked Hetzner (again). I had the same issue with some systems.
     
  3. brt

    brt New Member

    Thank you very much for your prompt response!

    Wow - without any warning, that’s really poor behavior. A lot of emails ended up in limbo (especially automated ones that can’t easily be resent), and my clients are far from happy.

    How can I verify that the spamhaus integration in Rspamd is still working correctly? Is there anything I need to be concerned about?
     
  4. remkoh

    remkoh Active Member HowtoForge Supporter

    Happens on a regular basis.
    Hetzner and others host a lot of vps servers. A big part of those are managed by people that don't have a clue what so ever. Especially wen it comes to security. Those systems then get abused by hackers/spammers and that way whole IP blocks get blocked.
     

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