250 repose from EHLO is an authentication failure?

[nurbles]

I just updated to the latest (v1.6.x) roundcube and I've discovered that I cannot SEND mail through it.  It will check and read mail great and the updated skins look better than ever.  But it keeps logging this when I try to send a message:

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[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> PHP Error: SMTP server does not support authentication (POST /cube/?_task=mail&_unlock=loading1773962183086&_framed=1&_lang=en&_action=send)
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> SMTP Error: Authentication failure: SMTP server does not support authentication (Code: ) in /usr/share/roundcube/program/lib/Roundcube/rcube.php on line 1702 (POST /cube/?_task=mail&_unlock=loading1773962183086&_framed=1&_lang=en&_action=send)
postfix/smtpd logs this:

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Mar 19 19:16:23 mail postfix/smtpd[37259]: connect from localhost[127.0.0.1]
Mar 19 19:16:23 mail postfix/smtpd[37259]: disconnect from localhost[127.0.0.1] ehlo=1 quit=1 commands=2
my roundcube config.inc.php contains:

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$config['smtp_host'] = 'tls://mail.e-visions.com:587';
$config['smtp_helo_host'] = 'mail.e-visions.com';
$config['smtp_user'] = '%u';
$config['smtp_pass'] = '%p';the roundcube stmp.log shows

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[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Connecting to localhost:587...
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 220 mail.e-visions.com ESMTP Postfix
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Send: EHLO mail.electronicvisions.com
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-mail.e-visions.com
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-PIPELINING
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-SIZE 320000000
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-ETRN
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-STARTTLS
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-ENHANCEDSTATUSCODES
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-8BITMIME
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250-DSN
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 250 CHUNKING
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Send: QUIT
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> Recv: 221 2.0.0 Byeand, finally, roundcube's errors.log showed this:

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[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> PHP Error: SMTP server does not support authentication (POST /cube/?_task=mail&_unlock=loading1773962183086&_framed=1&_lang=en&_action=send)
[19-Mar-2026 19:16:23 -0400]: <lr4s9h9e> SMTP Error: Authentication failure: SMTP server does not support authentication (Code: ) in /usr/share/roundcube/program/lib/Roundcube/rcube.php on line 1702 (POST /cube/?_task=mail&_unlock=loading1773962183086&_framed=1&_lang=en&_action=send)
I am absolutely NOT an expert on this stuff, but the "(Code: )" in the last line above looks suspicious to me (as a developer myself) and as I read the SMTP protocol, the 250 response to the EHLO is success, so why is roundcube giving up?  Or may PHP is giving up?  I'm running

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PHP 7.4.3-4ubuntu2.29+esm3 (cli) (built: Jan  7 2026 08:36:14) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.3-4ubuntu2.29+esm3, Copyright (c), by Zend Technologiesin case there's a known issue with it.

If there is anything else I can provide to help figure this out and restore the ability to send email!  Thank you!

[JohnDoh]

As your SMTP server does not support authentication you should set the SMTP auth config vars to empty strings in your Roundcube config.

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


[alec]

That's no the problem. AUTH capabilities should get listed after establishing a secure connection, but for some reason Roundcube does not use STARTTLS command. I'm not sure why when smtp_host has tls:// prefix. Lack of php-ssl module? Or you don't tell us truth.

[nurbles]

I'm curious where roundcube is getting the host name it is using in the EHLO message.  That domain name only appears in the xskin/config.inc.php file where local assets are use for some skin features.  Why is roundcube not using the smtp_host name from roundcube/config/config.inc.php?  Is there some other place where this type of setting might be stored that I have not found?  If so, there might be other settings overriding that are causing my problems.

I should also mention that roundcube v1.3.x was working just fine (and successfully logging in to send mail) for over SIX YEARS.  However, after updating the system from Ubuntu 18.04 to 20.04, roundcube no longer connects.

One of my users also discovered that his email client was only using TLS 1.0 and we needed to make a configuration change for him so that his mail client would support TLS v1.2, which is now required.  Is there any chance something like that is biting me here?