"Enable messaging system" (Site administration > Advanced features) is supposed to control messaging between site users only. However, when the setting is disabled, in addition to removal of "My profile > Messages" (which is fine, trying to access this page directly gives an error) it removes "My profile settings > Messaging" which should remain there as it allows user to control many other message types delivery methods (in fact, this page is still accessible if called directly, e.g. moodle/message/edit.php?id=2&course=1, only menu item is removed).

The solution probably should be along these lines:

• "My profile settings > Messaging" should not disappear from the menu when "Enable messaging system" is disabled.
• "Personal messages between users" type should not be listed in "My profile settings > Messaging" preference page when "Enable messaging system" is disabled.