In T115095#3004776, @Bawolff wrote:

Review of 631882e3779 of Newsletter extension (Jan 29, 2017)

Anyone with newsletter-create rights can edit a Newsletter namespace page (via api). While these changes aren't reflected in the relavent tables, they can make things inconsistent and confusing (e.g. Have the page display a different list of publishers than the actual list). Newsletter-manage permissions should apply to editing Newsletter pages via the api like it does during normal editing. The most obvious way to do this is with a getUserPermissionsErrors (or similar) hook. However, it may also be better to make the content handler page canonical and use it instead of the separate db tables where possible to eliminate the possibility of inconsistency in the system.