mail is missing in my Macbook Air (5 days only)

Hi all,
So during the Thanksigiving break I didn't use my Macbook Air (version10.8.2). However, I continued to receive and view mail from both my gmail and yahoo accounts on both my iPad and iPhone. And, you guessed it, when I fired up my MacBook Air on Nov. 26th I was missing mail from the last 5 days, even though I clearly received mail on the other devices AND I'm receiving mail today (no problems).

1) How do I push/pull those missing 5 days into the Macbook Air?
and
2) How do I avoid this problem in the future?

Many thanks for any help!