So if I'm right, $rcmail_config['smtp_user'] and $rcmail_config['plugin_manager_admins'] must point to the same account. I've made changes, downloaded plugins, uploaded them to my server, cheked box at idle_timeout, but there is settings for it?
Not sure if you looked at your plugins configuration yet... idle_timeout plugin has the following options:
.../plugins/idle_timeout/
config.inc.php/* warn after (x) minutes after idle is detected */
$rcmail_config['idle_timeout_warning'] = 18;
/* logout after (x) minutes when logout warning has been displayed */
$rcmail_config['idle_timeout_logout'] = 2;
/* database table */
$rcmail_config['db_table_timeout'] = 'timeout';
And why, everytime I log in with admin account I see page for selecting plugins to download?
plugin_manager is not different than other plugins hence you must adjust its configuration as you do with each one of your plugins.
.../plugins/plugin_manager/
config.inc.php/* Show update page after login */
$rcmail_config['plugin_manager_show_updates'] = true; <=== change its value to "false" and it won't display after every login:
$rcmail_config['plugin_manager_show_updates'] = false;