Here are the categories I'm thinking would make the most sense for each page.

For "Recommendations for moving to production", I'd recommend creating some kind of "Best Practices" or "Recommendations" category to fit it under. It doesn't really fit the category of an overview or a how-to guide - it's moreso a page recommending the best way to do something, without going into detail on how to do it.
The "Sending outbound email" page would fit in this category as well, since it covers best practices.

I think "Cloud VPS user roles and rights" and "Cloud VPS IP space" would better fit underneath a "Reference Documentation" category than "Overview" - but Overview seemed to be the closest category currently-available.

As a follow-up to this ticket, it might not be a bad idea to specify recommended categories for the templates in the documentation toolkit here: https://www.mediawiki.org/wiki/Documentation/Toolkit#Use_templates_to_create_documentation

So for example, if someone's creating a how-to guide using the template - it would make sense for the template to specify they should apply the "How-to guide" Category to the article.

Thanks for working on this, @Junkyard1625! Re: your suggestion that the documentation toolkit should refer to the doc type categories: unfortunately those categories aren't consistently created (nor used) across all the wikis and other places where Wikimedia technical documentation is published, but that documentation toolkit does seek to provide guidance relevant for all those places. So, referring to categories that are only on Wikitech would be too specific for the Toolkit. It's definitely something we can work towards though (having more consistent doc type categories across wikis and other places where tech docs live). Thanks again for all your work on this!