Filter: postie_category_default

This filter is called to determine the default category for the post. This filter is called before the email is examined for categories and establishes the default category if none are specified in the email. Note that the category is an integer category id.

add_filter('postie_category_default', 'my_postie_category_default');

function my_postie_category_default($default_category) {
 $default_category = 1;
 return $default_category;