Q: Mail not automatically checking

I am having the same problem.

In the absence of any creative suggestions, I am hoping that the problem may go away with Mavericks.

One possible cause is if there is a message which is for some reason unpalatable to the mail server which prevents Apple Mail from getting the file and subsequent files from the server.  For example, a message could be too big.

Good suggestion, so I had a look on the server, but no mail there.

Also, I have noticed that there is nothing in the Activity window, so for some reason the check is not being initiated. 

Well, I guess if this were happening to me, I'd wonder if there were some incompatibility between Apple Mail and the mail server.  Maybe double-check the mail settings against what the mail server recommends.  Also, maybe watch the "Activity" window (Window, Activity) to see if Apple Mail is actually checking for mail and, if so, what is happening.  Also, maybe look at Console (Utilities folder) to look for any error messages which might give a clue.

Another thing to try is to double-check/reset Mail preferences. Maybe delete the Mail preferences file.

This only started happening to me recently, it is intermittant, and when it happens there is nothing in the Activity window, so my suspicions are:

- a problem with mail extensions

- a consequence of some OS X problem

But it is odd that only 2 people have reported having the problem.

Good suggestion, but deleting com.apple.mail.plist resulted in all my mailboxes disappearing, so I quickly restored it! 

Presumably there is a less drastic form of reset?

If you suspect some third party software conflict, you can test this hypothesis by starting up in Safe Mode and testing.

If the Safe Mode doesn't solve the problem, try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work. The intent is to see if it is specific to one account or a system wide problem. This account can be deleted later.

Isolating an issue by using another user account

I am having the same issue .. for the past 3-4 days.  Mac mail will check for mail only when it feels like it, but not the scheduled every 5 mins.  Sometimes it won't check at all.  I'm missing a lot of important work emails because of this.  If anyone has a solution (besides calling Apple), that would be great.

I am having the same problem and it appears to have started recently as it has only come to my attention in the past several weeks.  No changes to my system other than the standard OS updates. Using Mail V 6.6 which appears to be the "Friday, September 13, 2013 4:17 PM" version. I've tried all the usual tricks to shake off the issue but it has not gone away.