Can not receive Emails on my Mac

I can recieve emails on my iPad and iPhone, but not my macbook air. This has been happening for about a week now. I have linked all my devices with iCloud and has been working perfectly ever since I noticed I wasn't getting emails on my Macbook Air.

I am running OSX Mountain Lion (10.8.4) on my Macbbok Air. And all my other devices are up to date.

PS: I use a gmail account, I'm not sure if that would affect it.