Include categories in subscribers management page

I've just installed v2.7.5 of Subscribe by Email, and noticed that the Subscribers Management Page only allows subscribers to select particular *post types*, not *categories*; thus, if you are posting on different content using different categories but the same post type, your subscribers would receive emails from all categories you've selected for that post type. This does not seem like a good solution: in effect, we'd have to create a new custom post type for each different topic so that subscribers could customize which topic they'd subscribe to, effectively multiplying custom post types without good reason. Has there been a feature request to include categories on the Subscribers Management Page as well as post types?

Many thanks,

Jim P.