We have an Outlook forms designer who's requesting permission to publish forms to the Organizational Forms library so that everyone can access them. What's the recommended use for the Organizational Forms library? Is it wise to give users permission to this folder from Exchange System Manager (ESM)? Or should we create folders beneath this level and grant permissions from there?
Kudos to your forms designer for trying to make the most of Outlook's forms features. If you want message forms to be operable in your organization, you should publish them in the Organizational Forms library. The alternative is to publish each message form to each individual's Personal Forms library—but as you can imagine, making sure everyone has the latest version of each form would be a nightmare. A form for use strictly in a public folder, such as a custom contact form, can reside in the public folder's forms library.
You're correct that you use ESM to grant permissions to the Organizational Forms library because it's an Exchange system folder. However, although you can create multiple libraries to support additional languages, forms in the Organizational Forms library aren't organized in subfolders. All message forms for organizational use are published to the central Organizational Forms library.
All users should have Read access to the Organizational Forms library. You might want to restrict Write access (i.e. the ability to publish and update forms) to administrators and trusted developers or even to administrators only. In the latter case, you'd require developers to submit their forms to some evaluation process before an administrator publishes them.
You might also want to require developers to demonstrate that the form contains no potentially harmful code and that they've included information on the form's Properties page, including a version number, contact information, and description. Because you can't create a department-level Organizational Forms library, you might even want to use a system of form categories and subcategories to make it easier for users to identify forms for different departments or purposes.