Mail not syncing inbox of gmail account, but subfolders are being synced...

Hi All,

I ran in to some problems last weeks with 2 of my Macs, both exact same problem with the Mail.app.

For 2 weeks ago I did a totall fresh install of Mountain Lion on my late 2011 MacBook Air. Everything went very smooth and easy but I still have trouble with the mail app. I have 2 mail accounts, one Exchange (Company) and one Google Apps (Gmail) for private mail. The Exchange account is running like a charm but I have trouble getting the Gmail account in sync.

I noticed the inbox is only syncing new messages when the mail app is open or running in the background. When I received 10 mail (gmail) one my iPhone and iPad during the day, the moment I come home and open my MBA, the messages don't show up in my inbox... they are not downloaded!

Even when I mark them unread by either iPhone, iPad or by webmail, the messages are not downloaded to my inbox...

They are only downloaded when I open the mail app in the background, go to the webmail (gmail) and archive the new messages and de-archive them. Then the mail app is receiving the 'new' messages...

Today my new 27" iMac arrived and I installed my gmail account right away.... Guess what, same problem on my iMac...

The mail settings I used are exactly the same as I used on my old iMac (late 2009)....

Strange thing is, I use about 10 subfolders to sort my mail (server side) by mail rules. Those subfolders do stay in sync...

So here I'm I with two Macs I can't get in sync with my Google Apps / Gmail account...

Who can help out, it's driving me crazy!

Thanks,

Sander