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!