SMTP Error (): Authentication Failed!

Dear Experts!
Today, when I tried to send out email as usual from within my roundcube webmail, this fatal error happened! What should I do to repair it?!? Please help!


I try the very same email draft from within Thunderbird and I can send it out!
My system is Ubuntu 24.04, ISPConfig 3.2.12p1, with Nginx, Roundcube.

 

I find many of these in my mail.warn log; not sure whether they are related.

 

similar to this:
https://forum.howtoforge.com/thread...net-localhost-11332-connection-refused.82760/

 

DAMN! Rspamd is not running!!!

 

rspamd.log permission changed and denied for unknown reason!!!

Still not working though after having repaired the log permission.

 

I did a system OS update from Ubuntu 20.04 to 22.04, and then from 22.04 to 24.04 on early January 2025.

The last time I could send email successfully from within ISPConfig roundcube was 2024-Nov-08. So the possible culprit of this issue is the OS upgrades. Certain steps of the upgrade breaks roundcube mail sending.

Please share your ideas to repair my roundcube.

 

I have found these log in /var/log/nginx/error.log; seem nasty.

 

Solved!
Roundcube config.inc.php has changed a lot during the past several years.
I updated my old config.inc.php to the default distribution one and it can send mails.