The FETCH_REQUEST_BROKER_LOGGING parameter will tell the application to log information related to fetch requests in the directory named /var/www/iv/data/temp/broker/.  This information is useful for debugging problems with data collection or plugin errors. Here's what the  entry in const.php looks like:

define('FETCH_REQUEST_BROKER_LOGGING', 0);

The '0' indicates that logging is currently turned off. If you want to turn it on, just change the value to '1'. Log files will be named according to the date, i.e., YYYY-MM-DD.log

The EMAIL_LOGGING parameter will tell the application to log details of automatic email messages in the directory named /var/www/iv/data/temp/email/.  This information is useful for debugging problems related to automatic emailing. Here's what the  entry in const.php looks like:

define('EMAIL_LOGGING', 'N');

The 'N' indicates that logging is currently turned off. If you want to turn it on, just change the value to 'Y'. Log files will be named according to the date, i.e., YYYY-MM-DD.log

Note that a user should only be delivered favorite content once per day. Therefore, you may see debug entries similar to this example: "No Digest sent to <email address> since no favorite content has been updated since prior digest was sent."