Since GMail just "upgraded" their accounts with new features in the past several days, I've discovered that Apple's mail program has failed to retrieve my mail messages (last message is dated 11/28/13). If I run Gmail from a browser or use Thunderbird (which I haven't run in some time), they show up just fine so I can only surmise there is a bug in Apple's Mail programs still in Mavericks. I guess I'm going to move back to Thunderbird again, at least until it's fixed. And this started long after Apple posted their previous Gmail fix a couple of weeks ago. Edit: I found if I quit the Mail program and restart it then it starts getting the messages again. The problem is I have no idea if it will do it again. It makes it seem unreliable now.