Plesk Premium Email is slow or error 504 is displayed: Connection timed out after 10000 milliseconds

Alexander Davydov

Updated January 13, 2026 19:04

Plesk for Linux kb: technical ext: kolab

Applicable to:

Plesk Premium Email interface, its emails and other menus load slowly and may fail with 504 error message.
Following error messages can be found in /var/log/roundcubemail/errors.log file:

CONFIG_TEXT: PHP Error: Curl error: Connection timed out after 10000 milliseconds in /usr/share/pear/HTTP/Request2/Adapter/Curl.php on line 149 (GET /n9HYdwfLMCi5oBXo/?_task=mail)
PHP Error: Curl error: Connection timed out after 10001 milliseconds in /usr/share/pear/HTTP/Request2/Adapter/Curl.php on line 149 (GET /n9HYdwfLMCi5oBXo/?_task=mail&_mbox=INBOX&_action=compose)

Firewall does not permit recursive connections to the global IP address.

Connect to the Plesk server via SSH
Add the following row to /etc/hosts file using any text editors like vi-editor:

CONFIG_TEXT: 127.0.0.1 webmail.example.com

Alternative solution

Connect to the server via SSH
Configure /etc/roundcubemail/kolab_files.inc.php file in the following way:

CONFIG_TEXT: $config['kolab_files_url']='https://webmail.example.com/chwala';

Additional information regarding this configuration can be found in Kolab documentation.

Comments