[SOLVED] Roundcube SMTP Authentication Error Fix

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Hello,

I’m sharing this as a fix I found for Roundcube SMTP authentication error.

Freedombox Version: Debian GNU/Linux trixie/sid and FreedomBox version 23.13.
Roundcube Version: Roundcube Webmail 1.6-git

On Debian Testing, if Roundcube is updated, you will likely get an SMTP authentication failure message if trying to send e-mail.

To fix the error, I applied the following.

  1. Edit the Roundcube configuration file with sudo nano /etc/roundcube/config.inc.php
  2. Replace $config['smtp_host'] = 'localhost:587'; with $config['smtp_host'] = 'tls://%n:587';
  3. Exit nano (ctrl+x) and restart apache with sudo systemctl restart apache2

Explanation:
Roundcube requires that smtp tls authentication aligns with your certificate. To provide this, I added tls:// followed by %n to specify my domain.

Hope this helps anyone that comes along.

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