Best practice for SMTP notification setup on Docker

Troubleshooting
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1

Hi

I was able to find some posts about this topic, however I still don’t know the best way to implement it.

I tried to use the internal Posftix and O365 direct send (can’t send emails to people outside your organization).

Using docker install parameters:
-e MAIL_RELAY_HOST=‘domain.mail.protection.outlook.com’’

Error, no solution found so far:
Status: PID file exists, but instance is not running!

If I interpreted this correctly it is not supported for docker?

Checkmk containers do not currently support configuring credentials for a smart host. You can bind a postfix configuration or a configuration folder from the Docker node if you need it.

so I really need to setup a dedicated Docker for the SMTP Relay?

Thanks for your help

2

Hi Nicola,

Were you able to find a solution to the problem?
I’m currently facing the same thing.

3

Just tested with the latest docker image. Postfix is starting just fine…

image

4

Have you tried adding " --cap-add=SYS_PTRACE" to your docker command?

5

Hi together

That was the support feedback I got:
In this case, you’re using a docker container, so you need to create a separate Docker container to send Emails.

Checkmk containers currently do not support the configuration of access data for a smart host as described here:

Since you are using the Checkmk Cloud Edition, you can try bypassing postfix completely so that Checkmk forwards notifications directly to a smarthost. This is done by the synchronous SMTP, which is described in detail in the article about notifications. Here an authentication over SMTP is also possible: Notifications - via Email, SMS, ticket system and more
(this workaround did not work for me)

I will try now the suggestion from @chauhan_sudhir

6

@a.kupenov solved after adding suggested parameter for docker installation (–cap-add=SYS_PTRACE) and changed from port 25 (with EXO relay connector) to 587 ( SMTP AUTH client submission) because docker blocked outgoing traffic with port 25:
How to set up a multifunction device or application to send emails using Microsoft 365 or Office 365 | Microsoft Learn

and 9.3. Synchronous delivery for HTML emails:
Notifications - via Email, SMS, ticket system and more (checkmk.com)