Notification mails not send but Testmail working

Installation Issues
5

thanks for taking care of this:

I have already seen this post

and changed the config to the values suggested:

'EmailTransport' => [
    'default' => [
        'host' => 'smtp-relay.gmail.com',
        'port' => 587,
        'username' => 'support@edu-werkstatt.de',
        'password' => '*********************',
        // Is this a secure connection? true if yes, null if no.
        'tls' => true,
        //'timeout' => 30,
        'client' => '213.61.178.152',
        //'url' => null,
    ],
],

But still no luck.
What I do not understand is why is testmail working and the queue not. Is this a different process using another library or class? Or do I have to set up a MTA locally? But it should work right away, shouldn it?

Email configuration
---------------------------------------------------------------
Host: smtp-relay.gmail.com
Port: 587
Username: support@edu-werkstatt.de
Password: *********
TLS: true

Sending email from: EDU-Werkstatt Support <support@edu-werkstatt.de>
Sending email to: matthias.graehn@edu-werkstatt.de
---------------------------------------------------------------

Trace
[220] smtp-relay.gmail.com ESMTP j16sm327449wro.11 - gsmtp
> EHLO 213.61.178.152
[250] smtp-relay.gmail.com at your service, [213.61.178.154]
[250] SIZE 157286400
[250] 8BITMIME
[250] STARTTLS
[250] ENHANCEDSTATUSCODES
[250] PIPELINING
[250] CHUNKING
[250] SMTPUTF8
> STARTTLS
[220] 2.0.0 Ready to start TLS
> EHLO 213.61.178.152
[250] smtp-relay.gmail.com at your service, [213.61.178.154]
[250] SIZE 157286400
[250] 8BITMIME
[250] AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
[250] ENHANCEDSTATUSCODES
[250] PIPELINING
[250] CHUNKING
[250] SMTPUTF8
> AUTH LOGIN
[334] VXNlcm5hbWU6
> *****
[334] UGFzc3dvcmQ6
> *****
[235] 2.7.0 Accepted
> MAIL FROM:<*****>
[250] 2.1.0 OK j16sm327449wro.11 - gsmtp
> RCPT TO:<matthias.graehn@edu-werkstatt.de>
[250] 2.1.5 OK j16sm327449wro.11 - gsmtp
> DATA
[354] Go ahead j16sm327449wro.11 - gsmtp
> From: "EDU-Werkstatt Support" <*****>
To: matthias.graehn@edu-werkstatt.de
Date: Thu, 04 Feb 2021 14:27:11 +0000
Message-ID: <6a6aef38885f46beb59b72c8f140bbb4@edu-ws_vm_slave_duck>
Subject: Passbolt test email
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Congratulations!
If you receive this email, it means that your passbolt smtp configuration is working fine.

I am wondering why the /var/log/passbold.log ist still empty if something went wrong.

Any further ideas? Maybe I sould debug the cake file to see whats going on there.

Thanks and Regards
Matt