I'm new to Macs and have a question about my MacBook Air OSX 10.9.1 and mail. I'm getting a "Startup disk full" message\* and one thing I highly suspect is the mail. Even if it's not the culprit, I'm curious how things work. I set up the Mail Application to get email from my Gmail and two Yahoo accounts. As far as I can tell when I look at the Mail App, all my email I've ever received is there for me to look at. 

Is the MacBook really downloading all the email?  

How do I limit the email it downloads locally (to 2 weeks old and newer for example).

Where is the email stored on hard disk and can I delete it (without deleting on the Google and Yahoo Servers).

In the worst case, I'd be willing to simply remove the accounts from Mail and go back to simply looking at them through Safari. Will this remove the email from my local machine? If not, how do I do it?

I have attempted to research this and found some ideas on not storing mail locally. See for example:
<http://www.cnet.com/news/tip-change-mail-settings-to-save-hard-drive-space/>

However, when I look at my system, I don't see this option and I'm guessing this is for an older version of MacOS.
Thanks,

Dave

\*My general question about disk storage is: [Newbie question on getting back hard drive space](https://apple.stackexchange.com/questions/151728/newbie-question-on-getting-back-hard-drive-space)