How to handle Zammad monitoring alerts

Technical assistance
1

Hey,

the monitoring tells me:

Zammad is broken: ['Channel: Email::Notification out  #<Errno::ENETUNREACH: Network is unreachable - connect(2) for "mail.example.org" port 465>']. Actions: []

The logging tells me (the same - but also the container having the problem):

docker compose logs | grep -i error
zammad-scheduler-1      | E, [2025-12-09T12:01:16.933392#1-196420] ERROR -- : Can't use Channel::Driver::Smtp: #<Errno::ENETUNREACH: Network is unreachable - connect(2) for "mail.example.org" port 465>
zammad-scheduler-1      | E, [2025-12-09T12:01:16.933434#1-196420] ERROR -- : Network is unreachable - connect(2) for "mail.example.org" port 465 (Errno::ENETUNREACH)

When I debug it, it works:

root /opt/zammad # den zammad-zammad-scheduler-1
                    dP            dP                           dP   
                    88            88                           88   
88d888b. .d8888b. d8888P .d8888b. 88d888b. .d8888b. .d8888b. d8888P 
88'  `88 88ooood8   88   Y8ooooo. 88'  `88 88'  `88 88'  `88   88   
88    88 88.  ...   88         88 88    88 88.  .88 88.  .88   88   
dP    dP `88888P'   dP   `88888P' dP    dP `88888P' `88888P'   dP   
                                                                    
Welcome to Netshoot! (github.com/nicolaka/netshoot)
Version: 0.14

                                         
 ccf5b5babded  ~  nc -v mail.example.org 465
Connection to mail.example.org (1.2.3.4) 465 port [tcp/submissions] succeeded!
^C

I use this alias for network debugging:

alias den=network_debug
network_debug() { #docker exec network (run debug container with network of $1 container
    docker run --rm --network=container:$1 -it nicolaka/netshoot
}

So, I could’t reproduce the issue. After some time, the monitoring alert just disappeard. So in general,

  1. Is there a way to get more information about monitoring alerts? It’s not the first time there was a false alert.
  2. Is there a way to do a manual re-check?
  3. Do you have any advice what to do in my case? I explicitly did’t want to just restart the service…
2

In the past there were several users on this board with docker installations that had trouble with IPv6 connections, while it worked on console level (as it might fall back to IPv4).

Disable ipv6 or make it work (which is, in my opinion, the much better route for the future).

3

Indeed, seems like Docker networks are ipv4 only per default.

But this was just an example to ask how to handle alerts in general. A manual re-check would be nice. Then I could check the network traffic with tcpdump in this case.

4

The next successfull operation closes the incident. So in your case a successfull notification mail.

5

It’s a bit sad that you ignore my questions. It’s also not the first time. You can just say no if you want. I would prefer this instead of ghosting questions…

6

I missed the memo where I am required to answer all your questions, sorry. There‘s no manual recheck option.