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  3. Outbound Emails Queued — NXDOMAIN Error and Local DNS Resolution Issue

Outbound Emails Queued — NXDOMAIN Error and Local DNS Resolution Issue

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    • M Offline
      M Offline
      mrhakash
      wrote last edited by joseph
      #1

      Hello Cloudron Team and Community,

      I’m experiencing an issue with outbound email delivery from my Cloudron instance. Emails are consistently stuck in the "Queued for delivery" state, and logs indicate an NXDOMAIN error when attempting to deliver to external domains like Gmail.

      Environment Details
      Cloudron Version: 8.2.4

      OS: Ubuntu 24.04 (DigitalOcean Droplet)

      Domain: alphadot.io

      Hostname: my.alphadot.io

      PTR Record: Set correctly (IP → my.alphadot.io)

      DNS: Managed via Cloudflare

      Dynamic DNS: Enabled

      Port 25: Blocked by DigitalOcean (planning to use SMTP relay)

      Observed Behavior
      Outgoing emails remain in the queue.

      JSON mail logs include:

      "host": "NXDOMAIN",
      "info": "NXDOMAIN"

      dig @127.0.0.1 gmail.com mx returns:

      connection refused

      Troubleshooting Attempts
      Verified unbound.service is active.

      /etc/resolv.conf points to 127.0.0.1

      Unbound config (/etc/unbound/unbound.conf.d/cloudron-network.conf) includes:

      yaml
      Copy
      Edit
      server:
      interface: 127.0.0.1
      access-control: 127.0.0.0/8 allow
      Restarted Unbound and rechecked logs.

      ss -tulnp | grep :53 shows nothing listening on 127.0.0.1:53

      No firewall is currently applied to the droplet.

      Request for Guidance
      I’d greatly appreciate help understanding why local DNS resolution isn’t functioning properly in this setup. I’m unsure whether Unbound is misconfigured, failing to bind correctly, or if there's a conflict with systemd-resolved or Cloudron’s internal DNS handling.

      Any suggestions or recommended checks would be very helpful. Happy to provide further logs or details if needed.

      Thank you in advance.

      J 1 Reply Last reply
      1
      • M mrhakash

        Hello Cloudron Team and Community,

        I’m experiencing an issue with outbound email delivery from my Cloudron instance. Emails are consistently stuck in the "Queued for delivery" state, and logs indicate an NXDOMAIN error when attempting to deliver to external domains like Gmail.

        Environment Details
        Cloudron Version: 8.2.4

        OS: Ubuntu 24.04 (DigitalOcean Droplet)

        Domain: alphadot.io

        Hostname: my.alphadot.io

        PTR Record: Set correctly (IP → my.alphadot.io)

        DNS: Managed via Cloudflare

        Dynamic DNS: Enabled

        Port 25: Blocked by DigitalOcean (planning to use SMTP relay)

        Observed Behavior
        Outgoing emails remain in the queue.

        JSON mail logs include:

        "host": "NXDOMAIN",
        "info": "NXDOMAIN"

        dig @127.0.0.1 gmail.com mx returns:

        connection refused

        Troubleshooting Attempts
        Verified unbound.service is active.

        /etc/resolv.conf points to 127.0.0.1

        Unbound config (/etc/unbound/unbound.conf.d/cloudron-network.conf) includes:

        yaml
        Copy
        Edit
        server:
        interface: 127.0.0.1
        access-control: 127.0.0.0/8 allow
        Restarted Unbound and rechecked logs.

        ss -tulnp | grep :53 shows nothing listening on 127.0.0.1:53

        No firewall is currently applied to the droplet.

        Request for Guidance
        I’d greatly appreciate help understanding why local DNS resolution isn’t functioning properly in this setup. I’m unsure whether Unbound is misconfigured, failing to bind correctly, or if there's a conflict with systemd-resolved or Cloudron’s internal DNS handling.

        Any suggestions or recommended checks would be very helpful. Happy to provide further logs or details if needed.

        Thank you in advance.

        J Online
        J Online
        joseph
        Staff
        wrote last edited by
        #2

        @mrhakash said in Outbound Emails Queued — NXDOMAIN Error and Local DNS Resolution Issue:

        dig @127.0.0.1 gmail.com mx returns:

        connection refused

        You have to check host -t MX gmail.com 127.0.0.150 . Can you also run cloudron-support --troubleshoot for hints?

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