Where to find this folder and delete it ?

[soamz]

Hi..
Im using Apple Mail Application for all of my emails.
All of my emails are hosted at Google Apps.

Right now, I was just checking the Account Info and I see a lot of garbage of Trash and Sent stored in the mailbox.

I checked the email from Google apps site and its trash and sent is clean there.
So, that makes it clear that, this trash is getting saved somewhere in the imac.

So, where is it and how can i delete it ?
I want to save each KB of my space and use it productively.

Please see screenshots..

 

[300D]

330MB? Forget about it. There are several GIGABYTES of garbage in every system's library folders. That little bit of waste is a mere speck on your harddrive.

 

[soamz]

Still I would like to know where is it, so that I can clean..

And I use macKeeper to clean all those cache garbage each sunday.