Raw edition SMTP email. Postfix works, but HTML Email notifications don't

Troubleshooting
,
1

CMK version: 2.4.0p14.cre
OS version: Ubuntu 24.04.3 LTS

Error message:

Output of “cmk --debug -vvn hostname”: (If it is a problem with checks or plugins)

I’m trying to get SMTP notifications working in checkMK, but not having much luck. I’ve looked at the official documentation and everything seems to be configured correctly, but it’s not working. Here’s what I’ve done and what does work:

  1. I’ve installed postfix and configured it to relay through SMTP2GO. This works. I can run a test using the following string:
    echo "Test of postfix to SMTP in checkMK" | mail -s "Test email subject line" -a "``From:checkmk@mydomain.com``" ``myuser@mydomain.com``”
    The above test works. I can see a record of the outgoing email using “journalctl -t postfix/smtp”, I can see the email reach SMTP2GO, it shows as delivered, and it arrives in my mailbox.
  2. I’ve configured a fallback notification address in checkMK (support@mydomain.com).
  3. I have multiple users (including myself) configured and email addresses designated.
  4. I created an HTML Email notification targeting a device folder to trigger on state change > DOWN and email a specific user that has an email address assigned.
  5. I perform a test notification, targeting a system in the selected folder. The test notification matches the notification rule:
Test results

1 notification rule matches (1 global rule, 0 user rules)
1 notification would have been sent based on your notification rules (see table: 'Predicted notifications')

and it shows that an email should have been sent:
itdepartment HTML Email from, reply_to, host_subject, elements, graphs_per_notification, notifications_with_graphs, matching_rule_nr, matching_rule_text

However, no email is actually sent. If I check the postfix/smtp logs, there is no record of an email being generated. I’m stumped. Postfix works and the notification test works and says it’s triggering the notification, but no email is being generated. I also setup a Contact Group and added multiple users to it, then set the HTML Email notification to go there instead. I get the same result. Nothing in /postfix/smtp logs is generated when doing the notification test.

Is there something I’m missing here?

2

Hi @OneAOKGuy and welcome to the forum!

According to Setting up notifications by rules - 4.4. Testing notification rules you
need to explicitly “tell” your test to actually dispatch a notification, by checking the
option “Send out notification for specific method”. Otherwise it’s only a simulation
also signified by the text one sees (i.e. “would have been sent”) as in your log:

1 notification would have been sent based on your notification rules (see table: 'Predicted notifications')

HTH,
Thomas

1 Like
3

That was it! I figured it was some simple option somewhere that I was missing, since Postfix itself works. Thanks so much for the pointer!

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