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

Question

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.
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!

Answer 1

I found the answer from someone in the Apple Community Forums:
Here's the response back and forth:
Csound1
Re: mail is missing in my Macbook Air (5 days only)Dec 4, 2012 12:33 PM (in response to kenneth@california) 
Remove both of the accounts from Mail and re-enter them, you must choose Imap as the collection method, not POP
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kenneth@california california
This solved my questionRe: mail is missing in my Macbook Air (5 days only)Dec 4, 2012 1:11 PM (in response to Csound1) 
Sounds scary.  When I remove both accounts do I lose all of my downloaded email from years past?  Ideally, it would stay in the computer and then when I re-enter them it uploads the missing dates. Am I dreaming?
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Csound1
This helped meRe: mail is missing in my Macbook Air (5 days only)Dec 4, 2012 1:16 PM (in response to kenneth@california) 
So you don't bother to backup I assume? Are these Imap or POP accountsIf Imap did you create any local folders for storageIf POP everything is local so you MUST backup first. (Unless you have a current backup available) Then you won't lose any of your mail. FYI, Gmail is probably setup on your machine as Imap, Yahoo could be anything.