RoundCube SMTP error (454)

Ubuntu 20.04: REQUIRED
Webmin 1.981: REQUIRED
Virtualmin 6.17-3: REQUIRED
RoundCube 1.5.1: RECOMMENDED

For some reasons I cannot send out emails from RoundCube, I’m getting this error “SMTP error (454): Authentication failed.” at each attempt.
However, I’m able to receive emails.
Thanks for the inputs on how to fix this.

What does the log file say?

Also see

This is all I can see for today:
[Thu Dec 16 02:25:29.586607 2021] [authz_core:error] [pid 1557627:tid 139907611748096] [client] AH01630: client denied by server configuration: /home/sibhe/public_html/vendor/phpunit
[Thu Dec 16 03:09:44.972954 2021] [authz_core:error] [pid 1557628:tid 139908116752128] [client] AH01630: client denied by server configuration: /home/sibhe/public_html/.env
[Thu Dec 16 03:52:26.541792 2021] [authz_core:error] [pid 1557627:tid 139907016161024] [client] AH01630: client denied by server configuration: /home/sibhe/public_html/.env

Apparently, there is not error for that in “Apache Error Log”.

Did you check mail sending with usermin also?


And or same smtp user connect in a apllication on that box, as example a cms, or webshop…
Also smtp connect with a mailclient

So you can be sure it is smtp or roundcube-virtualminbox related

1 Like

I found the issue and will document it here for those who might have the same issue.

From your file manager, go to roundcube/config/ and remove the default SMTP user and password.

$ config['smtp_user'] = '%u';
$ config['smtp_pass'] = '%p';


$ config['smtp_user'] ='';
$ config['smtp_pass'] = '';

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