Sometimes a filter can cause emails to bypass your inbox and be sent to either the trash folder or a different folder. You may need to check any filters you've created to make sure your messages are correctly organized. Messages are often delivered the right way though very rarely there may be a delay in transit. This is usually due to problems on the mail server, heavy internet traffic, or routing problems. Unfortunately, other than waiting, you won't be able to determine if the message is delayed or undeliverable. If possible, to fix the AOL account not receiving emails, ask the sender to resend the message to see if you can get the message a second time.