[SOLVED] roundcube cannot send mails / does not support auth

Hi!

Here runs debian 12, ispconfig 3.3.0p3, roundcube 1.6.5.

"Suddently" roundcube cannot send any mails.

Code:

#/var/log/roundcube/errors.log
[12-Nov-2025 19:32:27 +0100]: <767q2ckb> PHP Error: SMTP server does not support authentication (POST /webmail/?_task=mail&_unlock=loading1762972342985&_framed=1&_action=send)
[12-Nov-2025 19:32:27 +0100]: <767q2ckb> SMTP Error: Authentication failure: tesoro2.mydomain.at
PIPELINING
SIZE
VRFY
ETRN
STARTTLS
ENHANCEDSTATUSCODES
8BITMIME
DSN
CHUNKING (Code: 250) in /usr/share/roundcube/program/lib/Roundcube/rcube.php on line 1787 (POST /webmail/?_task=mail&_unlock=loading1762972342985&_framed=1&_action=send)

I can't say how long it hasn't been working, as webmail is rarely used. It definitely worked seven months ago.
Sending emails via Thunderbird, AppleMail, and the iPhone mail client works perfectly.

I checked some configuration files of roundcube, but I didn't find anything unusual (for me). Any ideas where I should look for some config-issues?

Thanks for hints!

 

Oh - just solved this issue.

In /etc/roundcube/config.inc.php I changed the line

Code:

$config['smtp_host'] = 'localhost:587';

to

Code:

$config['smtp_host'] = 'tls://%n:587';

and restarted apache2 by
systemctl restart apache2

Now roundcube sends mails again.

 

So you changed /etc/roundcube/config.inc.php some time before? Must have been.
Because default is

Code:

$config['smtp_host'] = 'localhost:25';

Apparently you changed the port to 587, which made use of tls mandatory.
And by that made changing localhost to %n mandatory to comply with the certificate.