Cannot send email from Roundcube: 4.7.1 Relay access denied

Symptoms

• It is not possible to send mail via Roundcube:

  PLESK_ERROR: SMTP Error (535): Authentication failed.

• The following error can be found in /var/log/maillog:

  postfix/smtpd[30391]: NOQUEUE: reject: RCPT from example.hostname.com[::1]: 454 4.7.1 <[email protected]>: Relay access denied; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<webmail.test.com>

• There is no user value in Roundcube’s configuration file:

  # grep smtp_user /usr/share/psa-roundcube/config/main.inc.php
  $rcmail_config[‘smtp_user’] = ”;

  OR

  # grep smtp_user /usr/share/psa-roundcube/config/defaults.inc.php
  $config[‘smtp_user’] = ”;

Cause

Misconfiguration in Roundcube settings.

Resolution

1. Connect to the server via SSH

2. Edit config.inc.php file with any text editor and add smtp_user
parameter with %u value as follows:

   # grep smtp_user /usr/share/psa-roundcube/config/config.inc.php
   $config[‘smtp_user’] = ‘%u’;