Ben has a twelve-year-old Mac that runs Entourage for his email client with AOL. But it has stopped working. Then it started working again a month later on its own, then stopped receiving mail a month later. Leo suspects that AOL may be the culprit. But also, Entourage hasn't been updated in years because it was discontinued by Microsoft in favor of Outlook. But Leo doesn't like that option either because both store email in one giant file, forcing Ben to rebuild it when it gets corrupted. It's a terrible way to do email. That's why using a client that stores email in plain text files is better. What Leo recommends is to back up the PST file occasionally, because it will fail again. Also check the settings.
Leo also recommends just using a stock MacMail client, or go with Gmail as a provider. Ben can then have his AOL/Verizon account forward to Gmail. Leo also uses MailMate. It's not free, but it's good for the price.