I think I may have just deleted all my iCloud 'sent' mail. Please help!

I thought I was tidying up my iCloud mail this morning, and believed mistakenly that copies of my iCloud sent mail were stored locally on my Mac.

In my Mailbox Behaviors account preferences I unchecked 'store sent messages on the server' and also 'Delete sent messages when one month old'. Immediately I lost all my sent mail over one month old from my sent mail box. D'oh!

I've tried to access a copy of yesterday's 'Sent messages.mbox' folder from Time Machine but TM can't locate the folder.

Does anyone know of a workaround, or a way to retrieve all my old emails from the iCloud servers?

Any help would be very much appreciated. I'm looking at about 10 years of odl Mac.com and MobileMe mail... may be a blessing really but there are probably a few important things in there.