The can be accessed from the main page by following these menus:
My Account --> Settings --> Settings and Privacy
Then under "General", verify the "Inbound Mail" setting
In some cases, folks who had "Any users may send you mail messages" checked have found that option mysteriously disabled. Without that option checked, you should still be able to receive mail from Friends, but not from other users.
Please make sure your settings reflect your wishes so you don't miss out on messages
