# Outbound mail to blocked: Spamhaus “open resolver” return code – need help with YunoHost DNS/Rspamd setup

**URL:** https://forum.yunohost.org/t/outbound-mail-to-blocked-spamhaus-open-resolver-return-code-need-help-with-yunohost-dns-rspamd-setup/40469
**Category:** Support
**Tags:** english
**Created:** [October 18, 2025, 6:40am UTC](https://forum.yunohost.org/t/outbound-mail-to-blocked-spamhaus-open-resolver-return-code-need-help-with-yunohost-dns-rspamd-setup/40469 "2025-10-18T06:40:14Z")
**Posts on this page:** 1
**Showing post:** 48

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### Author: ![AT69](https://forum.yunohost.org/letter_avatar_proxy/v4/letter/a/ecd19e/32.png) [@AT69](https://forum.yunohost.org/u/AT69)
#### Post date: [October 23, 2025, 5:22am UTC](https://forum.yunohost.org/t/outbound-mail-to-blocked-spamhaus-open-resolver-return-code-need-help-with-yunohost-dns-rspamd-setup/40469/48 "2025-10-23T05:22:52Z")

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Good morning, I installed the new Yunohost 12.1.31 update and ended up on the spam list again. Until now everything had been quiet. When I run the diagnosis in Yunohost, I get this suggestion — do I have to do that?

Deine IP-Adresse oder Domäne `65........` ist auf der Blacklist auf Spamhaus ZEN

- It looks like the reason mentions ‘open resolver’.  
This usually means your server is not using its local DNS, but a public, open, one.  
Check the contents of `/etc/resolv.conf`, it should contain `nameserver 127.0.0.1`.  
Since this file is usually automatically generated, do not edit it manually. Check your DHCP settings, or your VPN settings if you are using one, or if you used a Debian image made by, for example, a VPS provider, look for a `cloudinit` configuration.  
You are most welcome on the YunoHost support channels to get help on this issue.  
The verbatim blacklist reason is: “Error: open resolver; [https://check.spamhaus.org/returnc/pub/2001:19f0:5000:1800:5400:5ff:fe01:2dc5/](https://check.spamhaus.org/returnc/pub/2001:19f0:5000:1800:5400:5ff:fe01:2dc5/)”
- Nachdem Sie herausgefunden haben, weshalb Sie auf die Blacklist gesetzt wurden und dies behoben haben, zögern Sie nicht, nachzufragen, ob Ihre IP oder Ihre Domäne von [ZEN Blocklist | Combined IP DNSBLs for effective email filtering](https://www.spamhaus.org/zen/) entfernt werden kann

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