The syndicated_post hook allows you to write filters which alter, act on, or filter out each syndicated post that is about to be inserted into the WordPress posts table (if it is a new post) or have its record in the posts table updated (if it is an update to an existing post).

The filter passes two parameters to any registered filter functions: an associative array representing the data fields for all the data associated with this post (to be passed to wp_insert_post()), and an object of class SyndicatedPost which provides convenient methods for accessing data about the item, as well as data about the subscription and the live feed from which the item was syndicated.

Filters should either return the associative array for the post record, with any changes that you would like to make reflected in the contents of the array — or else should return a NULL value to indicate that the post should be filtered out rather than committed to the WordPress database.